CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (loss)	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2016		45,814				1,741
Beginning Balance at Dec. 31, 2016	$ 2,137,517	$ 45,814	$ 506,800	$ 2,194,593	$ (438,717)	$ (170,973)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	152,530			152,530
Cash dividends	(61,237)			(61,237)
Other comprehensive income (loss), net of tax	173,626				173,626
Settlement of convertible notes (in shares)		928				(503)
Settlement of warrants	4,832	$ 928	(48,375)			$ 52,279
Settlement of note hedges associated with convertible notes (in shares)						516
Settlement of note hedges associated with convertible notes	(7)		112,901			$ (112,908)
Shares issued under compensation plans (in shares)		129				(48)
Shares issued under compensation plans	23,182	$ 129	20,395			$ 2,658
Deferred compensation (in shares)						(2)
Deferred compensation	88					$ 88
Ending Balance (in shares) at Dec. 31, 2017		46,871				1,704
Ending Balance at Dec. 31, 2017	2,430,531	$ 46,871	591,721	2,285,886	(265,091)	$ (228,856)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	200,802			200,802
Cash dividends	(62,165)			(62,165)
Other comprehensive income (loss), net of tax	(75,994)				(75,994)
Settlement of convertible notes (in shares)						(412)
Settlement of warrants	(40)		(56,115)			$ 56,075
Shares issued under compensation plans (in shares)		377				(50)
Shares issued under compensation plans	42,899	$ 377	38,756			$ 3,766
Deferred compensation (in shares)						(10)
Deferred compensation	869		399			$ 470
Ending Balance (in shares) at Dec. 31, 2018		47,248				1,232
Ending Balance at Dec. 31, 2018	2,539,978	$ 47,248	574,761	2,427,599	(341,085)	$ (168,545)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	461,466			461,466
Cash dividends	(62,828)			(62,828)
Other comprehensive income (loss), net of tax	(3,307)				(3,307)
Shares issued under compensation plans (in shares)		288				(46)
Shares issued under compensation plans	44,952	$ 288	42,092			$ 2,572
Deferred compensation (in shares)						(4)
Deferred compensation	380		127			$ 253
Ending Balance (in shares) at Dec. 31, 2019		47,536				1,182
Ending Balance at Dec. 31, 2019	$ 2,979,320	$ 47,536	$ 616,980	$ 2,824,916	$ (344,392)	$ (165,720)