Income Taxes Income before income taxes (Details) (USD $)	3 Months Ended	12 Months Ended				3 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Related to current fiscal year [Member]	Mar. 31, 2013 Related to prior fiscal year reported in current fiscal year [Member]	Dec. 31, 2013 Related to prior fiscal year reported in current fiscal year [Member]
Tax benefit from extension of the short line tax credit					$ 25,900,000	$ 41,000,000	$ 41,000,000
Income tax expense, other than the 2012 retroactive benefit from the Short Line Tax Credit		87,200,000
Provision for income tax as a percentage of income before income taxes and income from equity investment other than the 2012 retroactive benefit from the Short Line Tax Credit		27.40%
Contingent forward sale contract mark-to-market expense	50,100,000	0	50,106,000	0
Income tax expense		46,296,000	46,402,000	38,531,000
Provision for income tax as a percentage of income before income taxes and income from equity investment other than non-deductible mark-to-market expense on contingent forward sale contract			34.80%
United States income before taxes		211,889,000	5,598,000	98,041,000
Foreign income before taxes		106,498,000	77,680,000	59,974,000
Total		318,387,000	83,278,000	158,015,000
Provision for United States income taxes applicable to undistributed foreign earnings		0
Undistributed foreign earnings		$ 268,900,000