Income Taxes (Details) - Components of Income Tax Expenses - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax expense:
U.S. federal	$ 48,339	$ 58,616	$ 48,801
State and local	434	11,292	10,300
Foreign	38,602	27,536	23,225
Total current	87,375	97,444	82,326
Deferred tax (benefit) expense:
U.S. federal	(176,046)	(61)	(884)
State and local	(14,363)	(349)	(702)
Foreign	(25,898)	(1,626)	1,550
Total deferred	(216,307)	(2,036)	(36)
Total current and deferred	(128,932)	95,408	82,290
Total tax (benefit) expense	(131,096)	94,849	96,576
Benefit (expense) relating to interest rate swaps used to increase (decrease) equity
Deferred tax (benefit) expense:
Other tax benefit (expense)	(2,477)	(1,113)	893
Benefit from stock transactions with employees used to increase equity
Deferred tax (benefit) expense:
Other tax benefit (expense)	46	52	13,960
Benefit (expense) relating to defined-benefit pension adjustments used to increase (decrease) equity
Deferred tax (benefit) expense:
Other tax benefit (expense)	$ 267	$ 502	$ (567)