Unaudited Condensed Consolidated Statement of Equity Statement - 9 months ended Sep. 30, 2017 - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2016	$ 1,095,247	$ 195,403	$ (5,998)	$ 990,203	$ (103,387)	$ 16,492	$ 2,534
Stockholders' Equity [Roll Forward]
Comprehensive income	329,637	0	0	0	299,347	30,169	121
Dividends declared on common stock	80,711	0	0	(37,011)	(43,700)	0	0
Employee share-based compensation earned	10,719	0	0	10,719	0	0	0
Stock option exercises	(30,672)	(2,476)	0	(28,196)	0	0	0
Restricted stock awards, net of forfeitures	0	207	0	207	0	0	0
Purchase of Company common stock	(148,818)	0	(4,794)	(24,904)	(119,120)	0	0
Noncontrolling Interest Payments	(60)	0	0	0	0	0	(60)
Noncontrolling Interest purchases	(4,580)	0	0	(2,258)		0	(2,322)
Other	6,845	452	0	6,393	0	0	0
Balance at end of period at Sep. 30, 2017	$ 1,238,951	$ 198,538	$ (10,792)	$ 971,131	$ 33,140	$ 46,661	$ 273