Consolidated Statements Of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands		Total		Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Adjustments for Accounting Changes [Member] Revision of Prior Period, Adjustment	AOCI Attributable to Parent	Treasury Stock	Noncontrolling Interest	Parent [Member]
Balance, beginning of period at Dec. 31, 2019				$ 310,000	$ 16,749	$ 1,903,703	$ 1,715,704	$ (7,772)	$ (11,705)	$ (319,660)	$ 54,999
Common stock repurchased		$ (56,500)								(56,517)
Unit amortization, net of forfeitures						88,717
Distributions under employee plans						(113,389)	(47,813)			60,895
Net income		315,003					315,003
Dividends declared, Common							(42,980)
Dividends declared, Preferred							(19,584)
Issuance of preferred stock				225,000		(7,005)
Dividends declared to equity-award holders						350
Unrealized gains on securities, net of tax	[1]	22,467
Unrealized gains on cash flow hedging activities, net of tax									(651)
Foreign currency translation adjustment, net of tax		(2,032)							(2,032)
Other						83	1,124
Deconsolidation of non-controlling interest											$ (54,999)
Balance, end of period at Sep. 30, 2020		4,030,687		535,000	16,749	1,872,459	1,913,682		8,079	(315,282)		$ 4,030,687
Balance, beginning of period at Jun. 30, 2020				535,000	16,749	1,847,608	1,818,335		(16,022)	(317,610)
Unit amortization, net of forfeitures						28,101
Distributions under employee plans						(3,403)	(302)			2,328
Net income		120,527					120,527
Dividends declared, Common							(14,042)
Dividends declared, Preferred							(9,897)
Issuance of preferred stock						15
Unrealized gains on securities, net of tax		19,123	[1]						19,123
Unrealized gains on cash flow hedging activities, net of tax									(2,968)
Foreign currency translation adjustment, net of tax		7,946							7,946
Other						138	(939)
Balance, end of period at Sep. 30, 2020		4,030,687		535,000	16,749	1,872,459	1,913,682		8,079	(315,282)		4,030,687
Balance, beginning of period at Dec. 31, 2020		4,238,766		535,000	16,749	1,888,982	2,078,135		27,639	(307,739)
Common stock repurchased		(86,400)								(84,723)
Unit amortization, net of forfeitures						93,840
Distributions under employee plans						(109,563)	(30,315)			67,714
Net income		563,468					563,468
Dividends declared, Common							(55,890)
Dividends declared, Preferred							(26,267)
Issuance of preferred stock				300,000		(9,279)
Redemption of preferred stock				(150,000)
Unrealized gains on securities, net of tax	[1]	(2,147)
Foreign currency translation adjustment, net of tax		(3,907)							(3,907)
Other						31	(404)
Balance, end of period at Sep. 30, 2021		4,791,324		685,000	16,749	1,864,011	2,528,727		21,585	(324,748)		4,791,324
Balance, beginning of period at Jun. 30, 2021				535,000	16,749	1,846,986	2,365,907		27,266	(283,118)
Common stock repurchased		(44,800)								(43,716)
Unit amortization, net of forfeitures						29,595
Distributions under employee plans						(3,266)	(1,169)			2,086
Net income		192,376					192,376
Dividends declared, Common							(18,586)
Dividends declared, Preferred							(9,689)
Issuance of preferred stock				300,000		(9,279)
Redemption of preferred stock				(150,000)
Unrealized gains on securities, net of tax		2,971	[1]						2,971
Foreign currency translation adjustment, net of tax		(8,652)							(8,652)
Other						(25)	(112)
Balance, end of period at Sep. 30, 2021		$ 4,791,324		$ 685,000	$ 16,749	$ 1,864,011	$ 2,528,727		$ 21,585	$ (324,748)		$ 4,791,324

[1] There were no reclassifications to earnings for the three and nine months ended September 30, 2021. Reclassifications to earnings were immaterial for the three and nine months ended September 30, 2020.