Condensed Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning Balance at Dec. 31, 2017		$ 1,751	$ 262,201	$ 1,809,845	$ (188,973)	$ (1,118,759)
Beginning Balance (in shares) at Dec. 31, 2017		110,385
Increase (Decrease) in Stockholders' Equity
Net income	$ 101,067
Other comprehensive (loss) income	$ (19,990)				(19,990)
Dividends declared on common stock				(22,556)
Dividends per share (usd per share)	$ 0.20
Stock compensation expense			7,420
Net issuance of treasury stock for vested restricted stock units (in shares)		233
Net issuance of treasury stock for vested restricted stock units			(1,062)			(1,995)
Adoption of accounting standards update related to leases				9,061
Ending Balance at Jun. 30, 2018	$ 838,010	$ 1,751	268,559	1,897,417	(208,963)	(1,120,754)
Ending Balance (in shares) at Jun. 30, 2018		110,618
Increase (Decrease) in Stockholders' Equity
Interest and other debt expense	62,894
Beginning Balance at Mar. 31, 2018		$ 1,751	265,022	1,853,351	(174,707)	(1,120,626)
Beginning Balance (in shares) at Mar. 31, 2018		110,569
Increase (Decrease) in Stockholders' Equity
Net income	55,343
Other comprehensive (loss) income	$ (34,256)				(34,256)
Dividends declared on common stock				(11,277)
Dividends per share (usd per share)	$ 0.10
Stock compensation expense			3,720
Net issuance of treasury stock for vested restricted stock units (in shares)		49
Net issuance of treasury stock for vested restricted stock units			(183)			(128)
Adoption of accounting standards update related to leases				0
Ending Balance at Jun. 30, 2018	$ 838,010	$ 1,751	268,559	1,897,417	(208,963)	(1,120,754)
Ending Balance (in shares) at Jun. 30, 2018		110,618
Increase (Decrease) in Stockholders' Equity
Interest and other debt expense	32,415
Beginning Balance at Dec. 31, 2018	881,265	$ 1,751	276,062	1,997,785	(268,808)	(1,125,525)
Beginning Balance (in shares) at Dec. 31, 2018		110,430
Increase (Decrease) in Stockholders' Equity
Net income	77,696
Other comprehensive (loss) income	$ 3,435				3,435
Dividends declared on common stock				(24,893)
Dividends per share (usd per share)	$ 0.22
Stock compensation expense			8,244
Net issuance of treasury stock for vested restricted stock units (in shares)		746
Net issuance of treasury stock for vested restricted stock units			(3,670)			(11,582)
Adoption of accounting standards update related to leases				(593)
Ending Balance at Jun. 30, 2019	$ 929,902	$ 1,751	280,636	2,049,995	(265,373)	(1,137,107)
Ending Balance (in shares) at Jun. 30, 2019		111,176
Increase (Decrease) in Stockholders' Equity
Interest and other debt expense	55,505
Beginning Balance at Mar. 31, 2019		$ 1,751	276,435	2,031,487	(272,431)	(1,137,035)
Beginning Balance (in shares) at Mar. 31, 2019		111,128
Increase (Decrease) in Stockholders' Equity
Net income	30,955
Other comprehensive (loss) income	$ 7,058				7,058
Dividends declared on common stock				(12,447)
Dividends per share (usd per share)	$ 0.11
Stock compensation expense			4,335
Net issuance of treasury stock for vested restricted stock units (in shares)		48
Net issuance of treasury stock for vested restricted stock units			(134)			(72)
Adoption of accounting standards update related to leases				0
Ending Balance at Jun. 30, 2019	$ 929,902	$ 1,751	$ 280,636	$ 2,049,995	$ (265,373)	$ (1,137,107)
Ending Balance (in shares) at Jun. 30, 2019		111,176
Increase (Decrease) in Stockholders' Equity
Interest and other debt expense	$ 28,401