Segment and Related Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Information about the revenues, operating results, goodwill and assets
Number of reportable segments | segment			4
Net interest income (expense)	$ 104,558	$ 107,284	$ 214,894	$ 215,573
Provision for (reversal of) credit losses	66,026	(672)	100,575	279
Noninterest income	468,125	276,703	739,838	492,666
Noninterest expense	370,209	304,088	652,110	582,835
Income from continuing operations before income taxes	136,448	80,571	202,047	125,125
Income (loss) from discontinued operations before taxes	30,430	(2,829)	34,444	3,980
Income before income taxes	166,878	77,742	236,491	129,105
Goodwill	267,447		267,447		$ 267,447
Assets of discontinued operations					248,429
Total assets	16,934,116		16,934,116		15,172,448
Operating segment | Banking
Information about the revenues, operating results, goodwill and assets
Net interest income (expense)	94,102	93,423	188,025	186,113
Provision for (reversal of) credit losses	65,600	(670)	99,875	355
Noninterest income	10,656	10,742	19,427	21,362
Noninterest expense	56,622	58,251	113,589	118,977
Income from continuing operations before income taxes	(17,464)	46,584	(6,012)	88,143
Income before income taxes	(17,464)	46,584	(6,012)	88,143
Goodwill	247,368		247,368		247,368
Total assets	13,575,474		13,575,474		11,147,344
Operating segment | Broker-Dealer
Information about the revenues, operating results, goodwill and assets
Net interest income (expense)	9,663	11,410	22,836	24,260
Provision for (reversal of) credit losses	426	(2)	700	(76)
Noninterest income	122,961	105,559	209,170	196,865
Noninterest expense	104,411	94,870	185,350	182,677
Income from continuing operations before income taxes	27,787	22,101	45,956	38,524
Income before income taxes	27,787	22,101	45,956	38,524
Goodwill	7,008		7,008		7,008
Total assets	2,954,978		2,954,978		3,457,068
Operating segment | Mortgage Origination Segment
Information about the revenues, operating results, goodwill and assets
Net interest income (expense)	(1,667)	(1,031)	(1,299)	(1,499)
Noninterest income	340,487	164,548	519,455	282,580
Noninterest expense	200,493	141,721	340,045	256,398
Income from continuing operations before income taxes	138,327	21,796	178,111	24,683
Income before income taxes	138,327	21,796	178,111	24,683
Goodwill	13,071		13,071		13,071
Total assets	2,972,527		2,972,527		2,357,415
Operating segment | Insurance Segment
Information about the revenues, operating results, goodwill and assets
Income (loss) from discontinued operations before taxes	(1,911)	(2,829)	2,103	3,980
Income before income taxes	(1,911)	(2,829)	2,103	3,980
Assets of discontinued operations					248,429
Total assets					248,429
Corporate
Information about the revenues, operating results, goodwill and assets
Net interest income (expense)	(3,232)	(1,331)	(4,888)	(2,661)
Noninterest income	550	648	2,838	1,360
Noninterest expense	8,888	9,274	13,741	24,836
Income from continuing operations before income taxes	(11,570)	(9,957)	(15,791)	(26,137)
Income (loss) from discontinued operations before taxes	32,341		32,341
Income before income taxes	20,771	(9,957)	16,550	(26,137)
Total assets	2,828,281		2,828,281		2,393,604
All Other and Eliminations.
Information about the revenues, operating results, goodwill and assets
Net interest income (expense)	5,692	4,813	10,220	9,360
Noninterest income	(6,529)	(4,794)	(11,052)	(9,501)
Noninterest expense	(205)	(28)	(615)	(53)
Income from continuing operations before income taxes	(632)	47	(217)	(88)
Income before income taxes	(632)	$ 47	(217)	$ (88)
Total assets	$ (5,397,144)		$ (5,397,144)		$ (4,431,412)