Consolidated Statement of Changes in Equity Statement - USD ($) $ in Thousands	Total	Conversion of Class B Common Stock to Class A Common Stock [Member]	Common Stock [Member] Class A Common Shares [Member]	Common Stock [Member] Class A Common Shares [Member] Conversion of Class B Common Stock to Class A Common Stock [Member]	Common Stock [Member] Class B Common Shares [Member]	Common Stock [Member] Class B Common Shares [Member] Conversion of Class B Common Stock to Class A Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] ASU 2018-02 [Member]	AOCL Attributable to Parent [Member]	AOCL Attributable to Parent [Member] ASU 2018-02 [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Stockholders' Equity, balance at Dec. 31, 2017	$ 3,896,092		$ 748		$ 7		$ 1,757,332	$ 2,234,864		$ (105,534)		$ (236,951)	$ 245,626
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Parent	75,098							75,098
Net Income Attributable to Noncontrolling Interest	927												927
Net income	76,025
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	10,345									10,345
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest													(4,018)
Other Comprehensive Income (Loss), Net of Tax	6,327
Value of stock issued for stock-based compensation	1,050		1				1,049
Compensation cost related to stock-based compensation	4,056						4,056
Value of treasury stock repurchased	(60,175)											(60,175)
United States Tax Cuts and Jobs Act 2017, Reclassification from AOCL to Retained Earnings	0									(2,970)
United States Tax Cuts and Jobs Act 2017, Reclassification from AOCL to Retained Earnings | Adjustments for New Accounting Principle, Early Adoption [Member]									$ 2,970		$ (2,970)
Other	1												1
Stockholders' Equity, balance at Mar. 31, 2018	3,923,376		749		7		1,762,437	2,312,932		(98,159)		(297,126)	242,536
Stockholders' Equity, balance at Dec. 31, 2018	3,630,052		752		5		1,785,005	2,482,252		(146,456)		(699,852)	208,346
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Parent	38,706							38,706
Net Income Attributable to Noncontrolling Interest	100												100
Net income	38,806
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(6,989)									(6,989)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest													818
Other Comprehensive Income (Loss), Net of Tax	(6,171)
Stock Issued During Period, Value, Conversion of Convertible Securities		$ 0		$ 1		$ 1
Value of stock issued for stock-based compensation	2,071		2				2,069
Compensation cost related to stock-based compensation	3,884						3,884
Value of treasury stock repurchased	(8,630)											(8,630)
Other	(2,732)						(832)	(1,104)					(796)
Stockholders' Equity, balance at Mar. 31, 2019	$ 3,657,280		$ 755		$ 4		$ 1,790,126	$ 2,519,854		$ (153,445)		$ (708,482)	$ 208,468