Unaudited Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Stockholders' Equity beginning balance at Dec. 31, 2019	$ 3,711,616	$ 124	$ 2,494,721	$ 4,712,729	$ (972,465)	$ (2,523,493)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	147,060			147,060
Other comprehensive loss, net of tax	(619,659)				(619,659)
Acquisition of common stock	(530,237)		75,000			(605,237)
Share-based compensation	14,175		14,175
Issuance of common stock	73,274	1	73,273
Stockholders' Equity ending balance at Mar. 31, 2020	2,796,229	125	2,657,169	4,859,789	(1,592,124)	(3,128,730)
Stockholders' Equity beginning balance at Dec. 31, 2020	3,355,411	126	2,749,900	5,416,945	(1,363,158)	(3,448,402)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	184,239			184,239
Other comprehensive loss, net of tax	(117,861)				(117,861)
Acquisition of common stock	(170,382)					(170,382)
Share-based compensation	17,747		17,747
Issuance of common stock	27,345		27,344
Stockholders' Equity ending balance at Mar. 31, 2021	$ 3,296,499	$ 127	$ 2,794,991	$ 5,601,184	$ (1,481,019)	$ (3,618,784)