Stockholders’ Equity (Deficit) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			$ (103,660)	$ 178,721
Net income	$ 48,901	$ 53,590	114,034	111,636
Other comprehensive income (loss)	54,510	(581)	80,818	48,208
Dividends paid			(69,527)	(70,979)
Issuance of common stock			(4,823)	(3,783)
Conversion to common stock			0	0
Stock-based compensation expense			12,531	9,786
Repurchase of common stock				(194,776)
Balances, end of period	29,373	78,813	29,373	78,813
Preferred stock
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			1	1
Balances, end of period	1	1	1	1
Preference stock
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			483	505
Conversion to common stock			(20)	(16)
Balances, end of period	463	489	463	489
Common stock
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			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			148,125	161,280
Issuance of common stock			(28,567)	(22,592)
Conversion to common stock			(398)	(320)
Stock-based compensation expense			12,531	9,786
Balances, end of period	131,691	148,154	131,691	148,154
Retained earnings
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			5,107,734	5,155,537
Net income			114,034	111,636
Dividends paid			(69,527)	(70,979)
Balances, end of period	5,152,241	5,196,194	5,152,241	5,196,194
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			(940,133)	(888,635)
Other comprehensive income (loss)			80,818	48,208
Balances, end of period	(859,315)	(840,427)	(859,315)	(840,427)
Treasury stock
Increase (Decrease) in Stockholders' Equity
Balances, beginning of period			(4,743,208)	(4,573,305)
Issuance of common stock			23,744	18,809
Conversion to common stock			418	336
Repurchase of common stock				(194,776)
Balances, end of period	$ (4,719,046)	$ (4,748,936)	$ (4,719,046)	$ (4,748,936)