Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Retained Earnings		Treasury Stock	Shares Of Common Stock	Accumulated Other Comprehensive Income (Loss)
Dividends declared per share (usd per share)	$ 0.25
Beginning Period Balance at Dec. 31, 2019	$ 4,954,697		$ 1,219	$ 3,306,006	$ 1,652,248		$ (83,434)		$ 78,658
Shares outstanding, beginning balance (shares) at Dec. 31, 2019			119,781,605
Stockholders' Equity Disclosure [Rollforward]
Net earnings	(1,433,111)				(1,433,111)
Other comprehensive income - net unrealized gain on securities available-for-sale, net of tax	12,258								12,258
Restricted stock awarded and earned compensation, net of shares forfeited (shares)			194,916
Restricted stock awarded and earned stock compensation, net of shares forfeited	6,494		$ 2	6,492
Restricted stock surrendered (shares)			(106,021)					(1,953,711)
Restricted stock surrendered	(3,460)						(3,460)
Common stock repurchased under Stock Repurchase Program	(20)
Common stock repurchased under Stock Repurchase Program	(70,000)			(69,980)
Cash dividends paid	(71,206)			(71,206)
Ending Period Balance at Mar. 31, 2020	3,390,389		$ 1,201	3,171,312	213,854		(86,894)		90,916
Shares outstanding, ending balance (shares) at Mar. 31, 2020			117,916,789
Stockholders' Equity Disclosure [Rollforward]
New Accounting Pronouncement, Effect of Change on Net Income	(5,283)	[1]			(5,283)	[1]			0
Beginning Period Balance at Dec. 31, 2019	4,954,697		$ 1,219	3,306,006	1,652,248		(83,434)		78,658
Shares outstanding, beginning balance (shares) at Dec. 31, 2019			119,781,605
Stockholders' Equity Disclosure [Rollforward]
Net earnings	(1,399,907)
Ending Period Balance at Jun. 30, 2020	$ 3,452,898		$ 1,207	3,148,090	247,058		(88,495)		145,038
Shares outstanding, ending balance (shares) at Jun. 30, 2020			118,374,603
Dividends declared per share (usd per share)	$ 0.60
Beginning Period Balance at Mar. 31, 2020	$ 3,390,389		$ 1,201	3,171,312	213,854		(86,894)		90,916
Shares outstanding, beginning balance (shares) at Mar. 31, 2020			117,916,789
Stockholders' Equity Disclosure [Rollforward]
Net earnings	33,204				33,204
Other comprehensive income - net unrealized gain on securities available-for-sale, net of tax	54,122								54,122
Restricted stock awarded and earned compensation, net of shares forfeited (shares)			550,738
Restricted stock awarded and earned stock compensation, net of shares forfeited	6,289		$ 6	6,283
Restricted stock surrendered (shares)			(92,924)
Restricted stock surrendered	(1,601)						(1,601)
Cash dividends paid	(29,505)			(29,505)
Ending Period Balance at Jun. 30, 2020	$ 3,452,898		$ 1,207	3,148,090	247,058		(88,495)		145,038
Shares outstanding, ending balance (shares) at Jun. 30, 2020			118,374,603
Dividends declared per share (usd per share)	$ 0.25
Beginning Period Balance at Dec. 31, 2020	$ 3,594,951		$ 1,207	3,100,633	409,391		(88,803)		172,523
Shares outstanding, beginning balance (shares) at Dec. 31, 2020			118,414,853
Stockholders' Equity Disclosure [Rollforward]
Net earnings	150,406				150,406
Other comprehensive income - net unrealized gain on securities available-for-sale, net of tax	(66,142)								(66,142)
Restricted stock awarded and earned compensation, net of shares forfeited (shares)			743,444
Restricted stock awarded and earned stock compensation, net of shares forfeited	6,417		$ 8	6,409
Restricted stock surrendered (shares)			(52,655)
Restricted stock surrendered	(1,908)						(1,908)
Cash dividends paid	(29,587)			(29,587)
Ending Period Balance at Mar. 31, 2021	3,654,137		$ 1,215	3,077,455	559,797		(90,711)		106,381
Shares outstanding, ending balance (shares) at Mar. 31, 2021			119,105,642
Beginning Period Balance at Dec. 31, 2020	3,594,951		$ 1,207	3,100,633	409,391		(88,803)		172,523
Shares outstanding, beginning balance (shares) at Dec. 31, 2020			118,414,853
Stockholders' Equity Disclosure [Rollforward]
Net earnings	330,918
Ending Period Balance at Jun. 30, 2021	$ 3,846,681		$ 1,221	3,056,522	740,309		(96,887)		145,516
Shares outstanding, ending balance (shares) at Jun. 30, 2021			119,555,102
Dividends declared per share (usd per share)	$ 0.25
Beginning Period Balance at Mar. 31, 2021	$ 3,654,137		$ 1,215	3,077,455	559,797		(90,711)		106,381
Shares outstanding, beginning balance (shares) at Mar. 31, 2021			119,105,642
Stockholders' Equity Disclosure [Rollforward]
Net earnings	180,512				180,512
Other comprehensive income - net unrealized gain on securities available-for-sale, net of tax	39,135								39,135
Restricted stock awarded and earned compensation, net of shares forfeited (shares)			586,271
Restricted stock awarded and earned stock compensation, net of shares forfeited	8,989		$ 6	8,983
Restricted stock surrendered (shares)			(136,811)
Restricted stock surrendered	(6,176)						(6,176)
Cash dividends paid	(29,916)			(29,916)
Ending Period Balance at Jun. 30, 2021	$ 3,846,681		$ 1,221	$ 3,056,522	$ 740,309		$ (96,887)		$ 145,516
Shares outstanding, ending balance (shares) at Jun. 30, 2021			119,555,102

[1] Impact due to adoption on January 1, 2020 of ASU 2016-13, "Financial Instruments - Credit Losses (ASC 326): Measurement of Credit Losses on Financial Instruments," and the related amendments, commonly referred to as CECL.