CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated other comprehensive Income (loss)	Treasury Stock	Total
Balance, beginning at Dec. 31, 2018	$ 1,397	$ 2,495,853	$ 291,919	$ (132,195)	$ (132,135)	$ 2,524,839
Balance (in shares) at Dec. 31, 2018	134,874,302
Increase (Decrease) in Stockholders' Equity
Net income			142,357			142,357
Cash dividends declared			(69,984)			(69,984)
Equity-based awards	$ 2	4,093	(544)		(1,533)	2,018
Equity-based awards (in shares)	143,756
Common stock repurchased					(40,000)	(40,000)
Common stock repurchased (in shares)	(1,509,846)
Other comprehensive income, net of tax				100,211		100,211
Balance, ending at Jun. 30, 2019	$ 1,399	2,499,946	363,748	(31,984)	(173,668)	2,659,441
Balance (in shares) at Jun. 30, 2019	133,508,212
Balance, beginning at Mar. 31, 2019	$ 1,399	2,497,770	326,451	(78,754)	(133,664)	2,613,202
Balance (in shares) at Mar. 31, 2019	135,012,015
Increase (Decrease) in Stockholders' Equity
Net income			72,433			72,433
Cash dividends declared			(34,916)			(34,916)
Equity-based awards		2,176	(220)		(4)	1,952
Equity-based awards (in shares)	6,043
Common stock repurchased					(40,000)	(40,000)
Common stock repurchased (in shares)	(1,509,846)
Other comprehensive income, net of tax				46,770		46,770
Balance, ending at Jun. 30, 2019	$ 1,399	2,499,946	363,748	(31,984)	(173,668)	2,659,441
Balance (in shares) at Jun. 30, 2019	133,508,212
Balance, beginning at Dec. 31, 2019	$ 1,399	2,503,677	437,072	(31,749)	(270,141)	$ 2,640,258
Balance (in shares) at Dec. 31, 2019	129,928,479					129,928,479
Increase (Decrease) in Stockholders' Equity
Net income			58,914			$ 58,914
Cash dividends declared			(67,547)			(67,547)
Equity-based awards	$ 2	5,594	(626)		(1,661)	3,309
Equity-based awards (in shares)	156,178
Common stock repurchased					(5,000)	(5,000)
Common stock repurchased (in shares)	(217,759)
Other comprehensive income, net of tax				84,480		84,480
Balance, ending at Jun. 30, 2020	$ 1,401	2,509,271	415,296	52,731	(276,802)	$ 2,701,897
Balance (in shares) at Jun. 30, 2020	129,866,898					129,866,898
Balance, beginning at Mar. 31, 2020	$ 1,401	2,506,477	429,323	4,129	(276,645)	$ 2,664,685
Balance (in shares) at Mar. 31, 2020	129,827,968
Increase (Decrease) in Stockholders' Equity
Net income			20,049			20,049
Cash dividends declared			(33,765)			(33,765)
Equity-based awards		2,794	(311)		(157)	2,326
Equity-based awards (in shares)	38,930
Other comprehensive income, net of tax				48,602		48,602
Balance, ending at Jun. 30, 2020	$ 1,401	$ 2,509,271	415,296	$ 52,731	$ (276,802)	$ 2,701,897
Balance (in shares) at Jun. 30, 2020	129,866,898					129,866,898
Increase (Decrease) in Stockholders' Equity
Cumulative-effect adjustment of change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments			$ (12,517)			$ (12,517)