Allowance for Credit Losses - Commercial Real Estate and Commercial Loan Segments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	$ 758,874	$ 1,862,085
Year two	1,837,742	3,354,750
Year three	3,184,608	2,140,513
Year four	1,974,365	1,729,763
Year five	1,623,130	1,072,603
Prior	2,947,726	2,152,690
Revolving	789,248	912,643
Revolving Converted to Term During the Period	1,699	11,386
Total	13,117,392	13,236,433
Investor loans secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	541,743	1,351,350
Year two	1,354,913	2,386,517
Year three	2,301,001	1,437,278
Year four	1,352,833	988,649
Year five	938,701	674,159
Prior	1,909,229	1,374,935
Revolving	13,796	12,877
Revolving Converted to Term During the Period	0	0
Total	8,412,216	8,225,765
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	2,729,785	2,675,085
Investor loans secured by real estate | CRE non-owner-occupied | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	124,225	261,885
Year two	244,225	491,522
Year three	447,464	431,791
Year four	445,435	266,942
Year five	223,077	254,527
Prior	927,154	763,101
Revolving	10,779	11,114
Revolving Converted to Term During the Period	0	0
Total	2,422,359	2,480,882
Investor loans secured by real estate | CRE non-owner-occupied | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	4,016
Year two	25,477	34,360
Year three	9,581	5,794
Year four	14,151	10,558
Year five	12,408	16,961
Prior	73,255	33,734
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	134,872	105,423
Investor loans secured by real estate | CRE non-owner-occupied | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	2,299	25,844
Year three	71,735	11,480
Year four	32,941	10,517
Year five	43,392	10,782
Prior	21,639	29,598
Revolving	548	559
Revolving Converted to Term During the Period	0	0
Total	172,554	88,780
Investor loans secured by real estate | Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	5,309,592	5,171,356
Investor loans secured by real estate | Multifamily | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	372,435	950,089
Year two	946,666	1,610,011
Year three	1,564,508	878,233
Year four	763,445	634,268
Year five	611,026	349,549
Prior	812,130	516,452
Revolving	1,426	0
Revolving Converted to Term During the Period	0	0
Total	5,071,636	4,938,602
Investor loans secured by real estate | Multifamily | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	32,587	38,892
Year two	5,858	59,500
Year three	51,975	12,181
Year four	17,181	19,751
Year five	6,602	10,917
Prior	17,328	13,606
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	131,531	154,847
Investor loans secured by real estate | Multifamily | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	38,663
Year two	53,404	9,963
Year three	12,131	11,339
Year four	13,368	12,479
Year five	12,456	3,814
Prior	15,066	1,229
Revolving	0	420
Revolving Converted to Term During the Period	0	0
Total	106,425	77,907
Investor loans secured by real estate | Construction and land
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	316,458	321,993
Investor loans secured by real estate | Construction and land | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	12,496	55,785
Year two	65,447	40,860
Year three	28,996	4,604
Year four	1,425	11,238
Year five	4,081	0
Prior	5,139	6,412
Revolving	1,043	784
Revolving Converted to Term During the Period	0	0
Total	118,627	119,683
Investor loans secured by real estate | Construction and land | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	1,123
Year two	7,462	41,046
Year three	45,561	9,197
Year four	0	3,601
Year five	3,785	0
Prior	71	260
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	56,879	55,227
Investor loans secured by real estate | Construction and land | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	401
Year two	3,577	62,853
Year three	59,440	59,512
Year four	52,370	3,786
Year five	4,398	20,531
Prior	21,167	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	140,952	147,083
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	56,381	57,331
Investor loans secured by real estate | SBA secured by real estate | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	496
Year two	498	10,400
Year three	9,508	12,558
Year four	12,517	14,497
Year five	17,476	7,078
Prior	15,942	10,032
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	55,941	55,061
Investor loans secured by real estate | SBA secured by real estate | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	1,012
Year five	0	0
Prior	0	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	0	1,012
Investor loans secured by real estate | SBA secured by real estate | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	158
Year three	102	589
Year four	0	0
Year five	0	0
Prior	338	511
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	440	1,258
Business loans secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	132,455	344,058
Year two	333,341	516,400
Year three	454,173	422,995
Year four	367,772	446,733
Year five	410,952	267,062
Prior	736,867	529,565
Revolving	9,196	14,518
Revolving Converted to Term During the Period	0	246
Total	2,444,756	2,541,577
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	73,967	79,595
Business loans secured by real estate | SBA secured by real estate | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	510	3,253
Year two	3,237	7,637
Year three	7,517	11,840
Year four	11,357	15,069
Year five	11,448	5,707
Prior	21,384	18,742
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	55,453	62,248
Business loans secured by real estate | SBA secured by real estate | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	0
Year three	70	768
Year four	905	989
Year five	1,694	2,780
Prior	6,502	4,882
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	9,171	9,419
Business loans secured by real estate | SBA secured by real estate | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	0
Year three	0	1,384
Year four	1,347	1,987
Year five	2,124	1,514
Prior	5,872	3,043
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	9,343	7,928
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	2,029,984	2,114,050
Business loans secured by real estate | CRE owner-occupied | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	108,753	286,745
Year two	274,558	367,269
Year three	358,652	274,512
Year four	251,081	295,809
Year five	274,570	202,282
Prior	588,999	422,614
Revolving	8,946	10,393
Revolving Converted to Term During the Period	0	246
Total	1,865,559	1,859,870
Business loans secured by real estate | CRE owner-occupied | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	8,769
Year two	11,033	42,310
Year three	15,015	60,222
Year four	31,674	28,421
Year five	30,254	23,875
Prior	51,484	44,855
Revolving	0	3,875
Revolving Converted to Term During the Period	0	0
Total	139,460	212,327
Business loans secured by real estate | CRE owner-occupied | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	16,096
Year three	0	5,376
Year four	5,883	7,459
Year five	9,043	4,263
Prior	9,789	8,409
Revolving	250	250
Revolving Converted to Term During the Period	0	0
Total	24,965	41,853
Business loans secured by real estate | Franchise real estate secured
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	340,805	347,932
Business loans secured by real estate | Franchise real estate secured | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	23,192	37,262
Year two	36,483	79,926
Year three	69,701	65,619
Year four	58,245	96,672
Year five	80,716	19,046
Prior	36,800	22,927
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	305,137	321,452
Business loans secured by real estate | Franchise real estate secured | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	7,587
Year two	7,588	1,650
Year three	3,218	3,274
Year four	7,280	327
Year five	1,103	5,627
Prior	16,037	4,093
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	35,226	22,558
Business loans secured by real estate | Franchise real estate secured | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	442
Year two	442	1,512
Year three	0	0
Year four	0	0
Year five	0	1,968
Prior	0	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	442	3,922
Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	78,092	155,831
Year two	141,817	444,000
Year three	424,977	266,221
Year four	243,017	280,317
Year five	262,286	97,412
Prior	176,638	120,099
Revolving	741,521	854,568
Revolving Converted to Term During the Period	1,699	11,140
Total	2,070,047	2,229,588
Commercial loans | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	1,656,098	1,768,834
Commercial loans | Commercial and industrial | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	61,115	70,233
Year two	76,872	205,395
Year three	223,574	99,178
Year four	101,069	193,046
Year five	182,673	36,957
Prior	90,115	62,682
Revolving	316,224	394,124
Revolving Converted to Term During the Period	1,113	5,051
Total	1,052,755	1,066,666
Commercial loans | Commercial and industrial | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	1,507	49,883
Year two	28,732	50,743
Year three	31,098	35,813
Year four	25,613	13,427
Year five	10,383	12,922
Prior	16,090	13,948
Revolving	305,405	322,123
Revolving Converted to Term During the Period	101	2,469
Total	418,929	501,328
Commercial loans | Commercial and industrial | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	7,701
Year two	8,575	7,540
Year three	20,849	29,078
Year four	21,862	4,485
Year five	2,997	4,574
Prior	11,807	8,350
Revolving	117,839	136,253
Revolving Converted to Term During the Period	485	2,859
Total	184,414	200,840
Commercial loans | Franchise non-real estate secured
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	399,041	444,797
Commercial loans | Franchise non-real estate secured | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	15,398	21,409
Year two	21,160	145,392
Year three	102,790	88,171
Year four	78,320	38,010
Year five	34,932	21,956
Prior	31,020	23,479
Revolving	0	0
Revolving Converted to Term During the Period	0	502
Total	283,620	338,919
Commercial loans | Franchise non-real estate secured | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	6,198
Year two	6,056	15,754
Year three	35,273	5,454
Year four	8,527	8,164
Year five	8,362	18,415
Prior	18,588	3,626
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	76,806	57,611
Commercial loans | Franchise non-real estate secured | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	16,836
Year three	9,100	6,612
Year four	5,762	18,655
Year five	18,397	1,638
Prior	3,995	3,165
Revolving	1,361	1,361
Revolving Converted to Term During the Period	0	0
Total	38,615	48,267
Commercial loans | SBA non-real estate secured
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	14,908	15,957
Commercial loans | SBA non-real estate secured | 0% - 5.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	72	407
Year two	422	2,257
Year three	2,212	910
Year four	1,021	1,078
Year five	1,299	441
Prior	3,230	2,782
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	8,256	7,875
Commercial loans | SBA non-real estate secured | >5.00% - 10.00%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	0
Year three	0	648
Year four	490	1,596
Year five	1,518	169
Prior	1,102	1,652
Revolving	0	0
Revolving Converted to Term During the Period	0	259
Total	3,110	4,324
Commercial loans | SBA non-real estate secured | Greater than 10%
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	0	0
Year two	0	83
Year three	81	357
Year four	353	1,856
Year five	1,725	340
Prior	691	415
Revolving	692	707
Revolving Converted to Term During the Period	0	0
Total	3,542	3,758
Commercial loans | Total commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Year one	78,092	155,831
Year two	141,817	444,000
Year three	424,977	266,221
Year four	243,017	280,317
Year five	262,286	97,412
Prior	176,638	120,099
Revolving	741,521	854,568
Revolving Converted to Term During the Period	1,699	11,140
Total	$ 2,070,047	$ 2,229,588