Unaudited Condensed Consolidated Statement of Equity Statement - 6 months ended Jun. 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	256,916	0	0	0	243,183	13,598	135
Dividends declared on common stock	(52,529)	0	0	(37,010)	(15,519)	0	0
Employee share-based compensation earned	7,645	0	0	7,645	0	0	0
Stock option exercises	20,601	1,571	0	19,030	0	0	0
Restricted stock awards, net of forfeitures	0	207	0	(207)	0	0	0
Purchase of Company common stock	(120,064)	0	(3,970)	(20,675)	(95,419)	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	1,808	102	0	1,706	0	0	0
Balance at end of period at Jun. 30, 2017	$ 1,204,984	$ 197,283	$ (9,968)	$ 958,434	$ 28,858	$ 30,090	$ 287