cash payments for federal , state , and foreign income taxes were $ 238.3 million , $ 189.5 million , and $ 90.7 million for the years ended december 31 , 2015 , 2014 , and 2013 , respectively . the following table summarizes the changes related to pca 2019s gross unrecognized tax benefits excluding interest and penalties ( dollars in millions ) : .
what was the difference in millions of cash payments for federal , state , and foreign income taxes between 2013 and 2014?
( a ) in 2013 , pca acquired $ 65.2 million of gross unrecognized tax benefits from boise inc . that related primarily to the taxability of the alternative energy tax credits . ( b ) the 2013 amount includes a $ 64.3 million gross decrease related to the taxability of the alternative energy tax credits claimed in 2009 excise tax returns by boise inc . for further discussion regarding these credits , see note 7 , alternative energy tax credits . ( c ) the 2013 amount includes a $ 104.7 million gross decrease related to the conclusion of the internal revenue service audit of pca 2019s alternative energy tax credits . for further discussion regarding these credits , see note 7 , alternative energy tax credits . at december 31 , 2015 , pca had recorded a $ 5.8 million gross reserve for unrecognized tax benefits , excluding interest and penalties . of the total , $ 4.2 million ( net of the federal benefit for state taxes ) would impact the effective tax rate if recognized . pca recognizes interest accrued related to unrecognized tax benefits and penalties as income tax expense . at december 31 , 2015 and 2014 , we had an insignificant amount of interest and penalties recorded for unrecognized tax benefits included in the table above . pca does not expect the unrecognized tax benefits to change significantly over the next 12 months . pca is subject to taxation in the united states and various state and foreign jurisdictions . a federal examination of the tax years 2010 2014 2012 was concluded in february 2015 . a federal examination of the 2013 tax year began in october 2015 . the tax years 2014 2014 2015 remain open to federal examination . the tax years 2011 2014 2015 remain open to state examinations . some foreign tax jurisdictions are open to examination for the 2008 tax year forward . through the boise acquisition , pca recorded net operating losses and credit carryforwards from 2008 through 2011 and 2013 that are subject to examinations and adjustments for at least three years following the year in which utilized . 7 . alternative energy tax credits the company generates black liquor as a by-product of its pulp manufacturing process , which entitled it to certain federal income tax credits . when black liquor is mixed with diesel , it is considered an alternative fuel that was eligible for a $ 0.50 per gallon refundable alternative energy tax credit for gallons produced before december 31 , 2009 . black liquor was also eligible for a $ 1.01 per gallon taxable cellulosic biofuel producer credit for gallons of black liquor produced and used in 2009 . in 2013 , we reversed $ 166.0 million of a reserve for unrecognized tax benefits for alternative energy tax credits as a benefit to income taxes . approximately $ 103.9 million ( $ 102.0 million of tax , net of the federal benefit for state taxes , plus $ 1.9 million of accrued interest ) of the reversal is due to the completion of the irs .