| **Business and Summary of Significant Accounting Principles (Narratives) (Details) (USD $)** | 3 Months Ended | 6 Months Ended |               | 3 Months Ended | 6 Months Ended |              | 6 Months Ended | 3 Months Ended | 6 Months Ended |
|----------------------------------------------------------------------------------------------|----------------|----------------|---------------|----------------|----------------|--------------|----------------|----------------|----------------|
||
| **Business**                                                                                 |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Year founded                                                                                 |           |           | 1979          |           |           |         |           |           |           |   |   |   |   |   |   |
| **Principles of Consolidation**                                                              |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Number of VIEs                                                                               |           |           | 4             |           |           |         |           |           |           |   |   |   |   |   |   |
| **Acquisition**                                                                              |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Percentage of voting interests acquired                                                      |           |           |          |           |           |         |           |           |           |   |   | 66.66% |   |   |   |
| **Earnings Per Share**                                                                       |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Shares contingently issuable                                                                 | 0              | 50,000         |          |           |           |         |           |           |           |   |   |   |   |   |   |
| **Common Stock**                                                                             |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Authorized amount, repurchase of stock                                                       |           |           | $ 5,000,000.0 |           |           |         |           |           |           |   |   |   |   |   |   |
| Stock repurchased during period, shares                                                      |           |           |          |           |           |         |           |           |           | 29,000 | 1,538,000 |   |   | 735,000 | 1,500,000 |
| Stock repurchased during period, value                                                       |           |           | 536,000       | 13,062,000     |           |         |           |           |           | 536,000 | 13,192,000 |   |   | 6,300,000 | 12,900,000 |
| Stock repurchase program, remaining value authorized to be repurchased                       |           |           |          |           |           |         |           |           |           |   |   |   | 116,100,000 |   |   |
| **Accounts Receivable and Allowance for Doubtful Receivables**                               |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Period past due for write-off of trade accounts receivable                                   |           |           | 120 days      |           |           |         |           |           |           |   |   |   |   |   |   |
| **Revenue Recognition**                                                                      |           |           |          |           |           |         |           |           |           |   |   |   |   |   |   |
| Revenues                                                                                     | 224,399,000    | 189,661,000    | 440,682,000   | 375,877,000    |           | 17,000,000   | 10,500,000     | 33,500,000     | 21,100,000     |   |   |   |   |   |   |
| Receivables                                                                                  | $ 203,550,000  |           | $ 203,550,000 |           | $ 228,372,000  | $ 47,400,000 |           | $ 47,400,000   |           |   |   |   |   |   |   |

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| - Definition
Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business.
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| - Definition
Percentage of voting equity interests acquired at the acquisition date in the business combination.
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| - Definition
Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.
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Number of shares that have been repurchased and retired during the period.
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| - Definition
Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).
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Amount of a stock repurchase plan authorized by an entity's Board of Directors.
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Amount remaining of a stock repurchase plan authorized by an entity's Board of Directors.
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Threshold period past due for trade accounts receivable to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
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| - Definition
Number of Variable Interest Entities (VIE) or potential VIEs for which the necessary information is unable to be obtained to: (1) determine whether the legal entity is a VIE, (2) determine whether it (the reporting entity) is the VIE's primary beneficiary, or (3) perform the accounting required to consolidate the VIE for which it is determined that it (the reporting entity) is the primary beneficiary.
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| - Definition
Shares issuable for little or no cash consideration upon the satisfaction of certain conditions (contingently issuable shares) are considered outstanding common shares and included in the computation of basic Earnings Per Share as of the date that all necessary conditions have been satisfied (in essence, when issuance of the shares is no longer contingent). Outstanding common shares that are contingently returnable (that is, subject to recall) are treated in the same manner as contingently issuable shares. Contingently issuable shares include shares that (a) will be issued in the future upon the satisfaction of specified conditions, (b) have been placed in escrow and all or part must be returned if specified conditions are not met, or (c) have been issued but the holder must return all or part if specified conditions are not met. The number of contingently issuable shares is determined by relating the portion of time within a reporting period that these shares have been outstanding to the total time in that period.
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Year the entity was founded, in CCYY format.
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