CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($)	Total	Series B Preferred Stock	Preferred Stock	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained Earnings Series B Preferred Stock
Beginning Balance (in shares) at Dec. 31, 2017			4,000,000	432,376,250	(11,087,337)
Beginning Balance, issued (in shares) at Dec. 31, 2017				443,463,587
Beginning Balance at Dec. 31, 2017	$ 2,474,256,000		$ 400,000,000	$ 88,693,000	$ (107,644,000)	$ 1,222,277,000	$ 2,748,000	$ 868,182,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	236,086,000							236,086,000
Other comprehensive income, net of tax	19,876,000						19,876,000
Total comprehensive income	$ 255,962,000
Reclassification resulting from the adoption of ASU No. 2018-02							592,000	(592,000)
Cash dividends:
Preferred Stock		$ (7,317,000)							$ (7,317,000)
Issuance of common shares (in shares)	5,944,946			5,944,946
Issuance of common shares	$ 18,852,000			$ 1,189,000		17,663,000
Stock-based compensation expense	$ 20,261,000					20,261,000
Common stock repurchased (in shares)	0
Shares repurchased related to employee stock-based compensation plans (in shares)	(2,940,595)			(2,940,595)	2,940,595
Shares repurchased related to employee stock-based compensation plans	$ (33,312,000)				$ (33,312,000)
Ending Balance (in shares) at Jun. 30, 2018			4,000,000	435,380,601	(14,027,932)
Ending Balance, issued (in shares) at Jun. 30, 2018				449,408,533
Ending Balance at Jun. 30, 2018	2,728,702,000		$ 400,000,000	$ 89,882,000	$ (140,956,000)	1,260,201,000	23,216,000	1,096,359,000
Beginning Balance (in shares) at Mar. 31, 2018			4,000,000	435,196,223	(13,827,355)
Beginning Balance, issued (in shares) at Mar. 31, 2018				449,023,578
Beginning Balance at Mar. 31, 2018	2,609,833,000		$ 400,000,000	$ 89,805,000	$ (138,629,000)	1,252,609,000	15,601,000	990,447,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,832,000							109,832,000
Other comprehensive income, net of tax	7,615,000						7,615,000
Total comprehensive income	$ 117,447,000
Cash dividends:
Preferred Stock		(3,920,000)							(3,920,000)
Issuance of common shares (in shares)	384,955			384,955
Issuance of common shares	$ 2,153,000			$ 77,000		2,076,000
Stock-based compensation expense	$ 5,516,000					5,516,000
Common stock repurchased (in shares)	0
Shares repurchased related to employee stock-based compensation plans (in shares)	(200,577)			(200,577)	200,577
Shares repurchased related to employee stock-based compensation plans	$ (2,327,000)				$ (2,327,000)
Ending Balance (in shares) at Jun. 30, 2018			4,000,000	435,380,601	(14,027,932)
Ending Balance, issued (in shares) at Jun. 30, 2018				449,408,533
Ending Balance at Jun. 30, 2018	2,728,702,000		$ 400,000,000	$ 89,882,000	$ (140,956,000)	1,260,201,000	23,216,000	1,096,359,000
Beginning Balance (in shares) at Dec. 31, 2018			4,000,000	435,681,488	(14,174,733)
Beginning Balance, issued (in shares) at Dec. 31, 2018				449,856,221
Beginning Balance at Dec. 31, 2018	2,972,656,000		$ 400,000,000	$ 89,972,000	$ (142,591,000)	1,274,635,000	10,623,000	1,340,017,000
Cash dividends:
Common Stock	(0.03)
Ending Balance (in shares) at Mar. 31, 2019			4,000,000	432,427,285	(20,899,600)
Ending Balance, issued (in shares) at Mar. 31, 2019				453,326,885
Ending Balance at Mar. 31, 2019	3,047,534,000		$ 400,000,000	$ 90,666,000	$ (216,710,000)	1,290,683,000	2,177,000	1,480,718,000
Beginning Balance (in shares) at Dec. 31, 2018			4,000,000	435,681,488	(14,174,733)
Beginning Balance, issued (in shares) at Dec. 31, 2018				449,856,221
Beginning Balance at Dec. 31, 2018	2,972,656,000		$ 400,000,000	$ 89,972,000	$ (142,591,000)	1,274,635,000	10,623,000	1,340,017,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	308,466,000							308,466,000
Other comprehensive income, net of tax	(24,202,000)						(24,202,000)
Total comprehensive income	284,264,000
Cash dividends:
Common Stock	(38,824,000)							(38,824,000)
Preferred Stock		(8,799,000)							(8,799,000)
Dividend equivalent units related to employee stock-based compensation plans	$ 0					5,000		(5,000)
Issuance of common shares (in shares)	3,651,684			3,651,684
Issuance of common shares	$ 3,026,000			$ 730,000		2,296,000
Stock-based compensation expense	$ 19,473,000					19,473,000
Common stock repurchased (in shares)	(11,424,755)			(11,424,755)	11,424,755
Common stock repurchased	$ (120,120,000)				$ (120,120,000)
Shares repurchased related to employee stock-based compensation plans (in shares)	(1,313,427)			(1,313,427)	1,313,427
Shares repurchased related to employee stock-based compensation plans	$ (14,360,000)				$ (14,360,000)
Ending Balance (in shares) at Jun. 30, 2019			4,000,000	426,594,990	(26,912,915)
Ending Balance, issued (in shares) at Jun. 30, 2019				453,507,905
Ending Balance at Jun. 30, 2019	3,097,316,000		$ 400,000,000	$ 90,702,000	$ (277,071,000)	1,296,409,000	(13,579,000)	1,600,855,000
Beginning Balance (in shares) at Mar. 31, 2019			4,000,000	432,427,285	(20,899,600)
Beginning Balance, issued (in shares) at Mar. 31, 2019				453,326,885
Beginning Balance at Mar. 31, 2019	3,047,534,000		$ 400,000,000	$ 90,666,000	$ (216,710,000)	1,290,683,000	2,177,000	1,480,718,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	150,277,000							150,277,000
Other comprehensive income, net of tax	(15,756,000)						(15,756,000)
Total comprehensive income	134,521,000
Cash dividends:
Common Stock	(25,804,000)							(25,804,000)
Preferred Stock		$ (4,331,000)							$ (4,331,000)
Dividend equivalent units related to employee stock-based compensation plans	$ 0					5,000		(5,000)
Issuance of common shares (in shares)	181,020			181,020
Issuance of common shares	$ 175,000			$ 36,000		139,000
Stock-based compensation expense	$ 5,582,000					5,582,000
Common stock repurchased (in shares)	(5,989,279)			(5,989,279)	5,989,279
Common stock repurchased	$ (60,120,000)				$ (60,120,000)
Shares repurchased related to employee stock-based compensation plans (in shares)	(24,036)			(24,036)	24,036
Shares repurchased related to employee stock-based compensation plans	$ (241,000)				$ (241,000)
Ending Balance (in shares) at Jun. 30, 2019			4,000,000	426,594,990	(26,912,915)
Ending Balance, issued (in shares) at Jun. 30, 2019				453,507,905
Ending Balance at Jun. 30, 2019	$ 3,097,316,000		$ 400,000,000	$ 90,702,000	$ (277,071,000)	$ 1,296,409,000	$ (13,579,000)	$ 1,600,855,000