Stockholders’ Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period	$ 53,370	$ 44,580	$ 66,395	$ 286,096
Net income (loss)	9,067	11,389	(2,618)	(200,423)
Other comprehensive income	(9,927)	22,690	(2,099)	26,571
Dividends paid	(8,725)	(8,594)	(26,050)	(25,693)
Issuance of common stock	1,708	774	(2,413)	(762)
Stock-based compensation expense	3,170	8,286	15,448	15,236
Balances, end of period	$ 48,663	$ 79,125	$ 48,663	$ 79,125
Dividends paid (USD per share)	$ 0.05	$ 0.05	$ 0.15	$ 0.15
Cumulative Effect
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period				$ (21,900)
Common stock
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period	$ 323,338	$ 323,338	$ 323,338	323,338
Balances, end of period	323,338	323,338	323,338	323,338
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period	5,903	68,498	68,502	98,748
Issuance of common stock	(6,610)	(9,272)	(81,487)	(46,472)
Stock-based compensation expense	3,170	8,286	15,448	15,236
Balances, end of period	2,463	67,512	2,463	67,512
Retained earnings
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period	5,172,185	5,188,119	5,201,195	5,438,930
Net income (loss)	9,067	11,389	(2,618)	(200,423)
Dividends paid	(8,725)	(8,594)	(26,050)	(25,693)
Balances, end of period	5,172,527	5,190,914	5,172,527	5,190,914
Retained earnings | Cumulative Effect
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period				(21,900)
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period	(831,303)	(836,262)	(839,131)	(840,143)
Other comprehensive income	(9,927)	22,690	(2,099)	26,571
Balances, end of period	(841,230)	(813,572)	(841,230)	(813,572)
Treasury stock
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period	(4,616,753)	(4,699,113)	(4,687,509)	(4,734,777)
Issuance of common stock	8,318	10,046	79,074	45,710
Balances, end of period	$ (4,608,435)	$ (4,689,067)	$ (4,608,435)	$ (4,689,067)