| **Net Income Per Share**          | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Earnings Per Share [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Net Income Per Share              | NET INCOME PER SHAREBasic net income per share is computed by dividing net income by the weighted-average shares outstanding during the reporting period. Diluted net income per share is computed by dividing net income by the combination of all dilutive common share equivalents, comprised of shares issuable under the Corporation’s share-based compensation plans, and the weighted-average shares outstanding during the reporting period.Dilutive common share equivalents include the dilutive effect of in-the-money share-based awards, which are calculated based on the average share price for each period using the treasury stock method. Under the treasury stock method, the exercise price of share-based awards, the amount of compensation expense, if any, for future service that the Corporation has not yet recognized, and the amount of estimated tax benefits that would be recorded in additional paid-in capital when share-based awards are exercised, are assumed to be used to repurchase common stock in the current period.The following table reconciles basic and diluted net income per share for the years indicated: 2014 2013 2012   Weighted-Average Shares     Weighted-Average Shares     Weighted-Average Shares  Basic net income per share:$60,162     $44,530     $45,122    Preferred stock dividends     (2,380)     (4,539)    Net income available to common stockholders60,162 36,266,356 $1.66 42,150 29,731,420 $1.42 40,583 28,632,915 $1.42Effect of dilutive stock options and warrants  288,253     276,960     213,769  Diluted net income per share:                 Net income available to common stockholders$60,162 36,554,609 $1.65 $42,150 30,008,380 $1.41 $40,583 28,846,684 $1.41  Options to purchase 543,514, 800,674, and 820,706 shares of common stock with weighted average exercise prices of $20.99, $21.32, and $21.58 at December 31, 2014, 2013 and 2012 respectively, were excluded from the computation of diluted net income per share because the options exercise price was greater than the average market price of the common stock. |

| X                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_EarningsPerShareAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The entire disclosure for earnings per share.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1278-109256Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=32703322&loc=d3e4984-109258Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.21) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688
+ Details**Name:**us-gaap_EarningsPerShareTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |