CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Treasury stock	Accumulated other comprehensive income (loss)	Retained earnings
Balance, beginning of period at Dec. 31, 2018		$ 371,353	$ 1,862,536	$ (175,059)	$ (124,214)	$ 1,647,275
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reissuance of treasury stock, net under share-based compensation plans			(11,582)	5,930
Equity compensation			9,624
Repurchase of common stock				(24,941)
Other comprehensive (loss) income, net of tax	$ 155,024				155,024
Net income	319,719					319,719
Cash dividends						0
Balance, end of period at Jun. 30, 2019	4,035,665	371,353	1,860,578	(194,070)	30,810	1,966,994
Balance, beginning of period at Mar. 31, 2019		371,353	1,856,236	(169,129)	(41,493)	1,799,216
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reissuance of treasury stock, net under share-based compensation plans			0	0
Equity compensation			4,342
Repurchase of common stock				(24,941)
Other comprehensive (loss) income, net of tax	72,303				72,303
Net income	167,778					167,778
Cash dividends						0
Balance, end of period at Jun. 30, 2019	4,035,665	371,353	1,860,578	(194,070)	30,810	1,966,994
Balance, beginning of period at Dec. 31, 2019	4,309,234	371,353	1,869,719	(283,196)	72,708	2,278,650
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reissuance of treasury stock, net under share-based compensation plans			(18,667)	9,768
Equity compensation			8,143
Repurchase of common stock				(119,997)
Other comprehensive (loss) income, net of tax	72,704				72,704
Net income	163,852					163,852
Cash dividends						(41,682)
Balance, end of period at Jun. 30, 2020	4,383,355	371,353	1,859,195	(393,425)	145,412	2,400,820
Balance, beginning of period at Mar. 31, 2020		371,353	1,855,371	(393,425)	1,224	2,407,305
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reissuance of treasury stock, net under share-based compensation plans			0	0
Equity compensation			3,824
Repurchase of common stock				0
Other comprehensive (loss) income, net of tax	144,188				144,188
Net income	14,047					14,047
Cash dividends						(20,532)
Balance, end of period at Jun. 30, 2020	$ 4,383,355	$ 371,353	$ 1,859,195	$ (393,425)	$ 145,412	$ 2,400,820