Consolidated Statement of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Accumulated Deficit(1)	Accumulated Other Comprehensive Income	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2014	$ 1,377,378	$ 205,458	$ (591)	$ 1,186,304	$ (81,859)	$ 59,414	$ 8,652
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	181,651	0	0	0	233,772	(53,250)	1,129
Dividends declared on common stock	(87,570)	0	0	(87,570)	0	0	0
Stock option exercises	31,931	3,054	0	28,877	0	0	0
Restricted stock awards, net of forfeitures	0	254	(9)	(245)	0	0	0
Employee share-based compensation earned	13,843		0
Purchase of Company common stock	(345,383)	0		13,843	0	0	0
Tax benefits related to stock-based awards	18,123	0	0	18,123	0	0	0
Purchase of noncontrolling interest	(2,075)	0	(12,455)	(71,664)	(261,264)	0	0
Acquisition		0	0	2,775	0	0	(4,850)
Noncontrolling interest payments	$ (222)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (222)
Retirement of treasury shares	0	(7,969)	(7,969)	0	0	0	0
Other	$ 1,725	$ 62	$ 0	$ 1,663	$ 0	$ 0	$ 0
Balance at end of period at Dec. 31, 2015	1,189,401	200,859	(5,086)	1,092,106	(109,351)	6,164	4,709
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	187,636	0	0	0	177,038	10,328	270
Dividends declared on common stock	(98,418)	0	0	(98,418)	0	0	0
Stock option exercises	17,662	2,108	0	15,554	0	0	0
Restricted stock awards, net of forfeitures	0	241	(1)	(240)	0	0	0
Employee share-based compensation earned	14,056	0	0	14,056	0	0	0
Purchase of Company common stock	(227,928)	0	(8,812)	(48,042)	(171,074)	0	0
Tax benefits related to stock-based awards	12,685	0	0	12,685	0	0	0
Purchase of noncontrolling interest	(1,961)	0	0	364	0	0	(2,325)
Noncontrolling interest payments	$ (120)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (120)
Retirement of treasury shares	0	(7,901)	(7,901)	0	0	0	0
Other	$ 2,234	$ 96	$ 0	$ 2,138	$ 0	$ 0	$ 0
Balance at end of period at Dec. 31, 2016	1,095,247	195,403	(5,998)	990,203	(103,387)	16,492	2,534
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	572,309	0	0	0	546,663	25,451	195
Dividends declared on common stock	(108,750)	0	0	(37,011)	(71,739)	0	0
Stock option exercises	33,611	2,759	0	30,852	0	0	0
Restricted stock awards, net of forfeitures	0	209	(2)	(207)	0	0	0
Employee share-based compensation earned	14,788	0	0	14,788	0	0	0
Purchase of Company common stock	(199,637)	0	(6,211)	(32,253)	(161,173)	0	0
Purchase of noncontrolling interest	(4,580)			2,258			(2,322)
Noncontrolling interest payments	$ (360)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 360
Retirement of treasury shares	0	(6,890)	(6,890)	0	0	0	0
Other	$ 6,809	$ 455	$ 0	$ 6,354	$ 0	$ 0	$ 0
Balance at end of period at Dec. 31, 2017	$ 1,409,437	$ 191,936	$ (5,321)	$ 970,468	$ 210,364	$ 41,943	$ 47