Consolidated Statement of Stockholders' Equity - 9 months ended Sep. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
BALANCE (in shares) at Dec. 31, 2017		25,515
BALANCE at Dec. 31, 2017	$ 1,124,282	$ 255	$ 291,461	$ 1,246,323	$ (123,226)	$ (290,531)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	127,054			127,054
Other comprehensive loss, net	(5,518)				(5,518)
Tax effects reclassified from accumulated other comprehensive loss	0			150	(150)
Purchases of treasury stock	(108,624)					(108,624)
Net issuance of treasury shares to employee stock compensation plans (in shares)		(21)
Net issuance of treasury shares to employee stock compensation plans	1,530		(14,996)			16,526
Stock-based compensation	14,203		14,203
Cash dividends, net of estimated forfeitures relative to participating securities	(15,978)			(15,978)
BALANCE (in shares) at Sep. 30, 2018		25,494
BALANCE at Sep. 30, 2018	1,148,346	$ 255	$ 290,668	1,368,946	$ (128,894)	$ (382,629)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of ASC 606 cumulative adjustment	$ 11,397			$ 11,397