Loans Receivable, Net - Credit Quality Indicators for Commercial Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Credit Quality Indicators By Origination
Total	$ 11,269,929	$ 11,122,696
Commercial real estate
Credit Quality Indicators By Origination
Term loans originated current fiscal year	521,791	1,496,094
Term loans originated fiscal year before current fiscal year	1,419,202	1,077,461
Term loans originated two years before current fiscal year	1,011,331	914,506
Term loans originated three years before current fiscal year	851,608	723,448
Term loans originated four years before current fiscal year	672,239	496,275
Term loans originated five years before current fiscal year	1,879,439	1,488,281
Revolving loans	119,091	119,830
Total	6,474,701	6,315,895
Commercial real estate | Pass
Credit Quality Indicators By Origination
Term loans originated current fiscal year	521,791	1,490,947
Term loans originated fiscal year before current fiscal year	1,413,986	1,069,503
Term loans originated two years before current fiscal year	1,000,493	874,673
Term loans originated three years before current fiscal year	810,910	696,371
Term loans originated four years before current fiscal year	645,700	481,392
Term loans originated five years before current fiscal year	1,825,762	1,450,596
Revolving loans	116,298	116,548
Total	6,334,940	6,180,030
Commercial real estate | Special Mention
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	0	0
Term loans originated two years before current fiscal year	0	0
Term loans originated three years before current fiscal year	0	0
Term loans originated four years before current fiscal year	0	0
Term loans originated five years before current fiscal year	0	0
Revolving loans	0	0
Total	0	0
Commercial real estate | Substandard
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	5,147
Term loans originated fiscal year before current fiscal year	5,216	7,958
Term loans originated two years before current fiscal year	10,838	39,833
Term loans originated three years before current fiscal year	40,698	27,077
Term loans originated four years before current fiscal year	26,539	14,883
Term loans originated five years before current fiscal year	53,593	37,574
Revolving loans	2,792	3,282
Total	139,676	135,754
Commercial real estate | Doubtful/ Loss
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	0	0
Term loans originated two years before current fiscal year	0	0
Term loans originated three years before current fiscal year	0	0
Term loans originated four years before current fiscal year	0	0
Term loans originated five years before current fiscal year	84	111
Revolving loans	1	0
Total	85	111
Other commercial
Credit Quality Indicators By Origination
Term loans originated current fiscal year	538,043	1,366,664
Term loans originated fiscal year before current fiscal year	974,231	304,430
Term loans originated two years before current fiscal year	281,749	241,222
Term loans originated three years before current fiscal year	223,210	269,857
Term loans originated four years before current fiscal year	241,634	179,225
Term loans originated five years before current fiscal year	378,212	218,306
Revolving loans	463,505	475,113
Total	3,100,584	3,054,817
Other commercial | Pass
Credit Quality Indicators By Origination
Term loans originated current fiscal year	538,039	1,341,316
Term loans originated fiscal year before current fiscal year	947,941	284,981
Term loans originated two years before current fiscal year	271,082	234,988
Term loans originated three years before current fiscal year	217,040	264,651
Term loans originated four years before current fiscal year	239,229	177,164
Term loans originated five years before current fiscal year	361,319	206,431
Revolving loans	436,725	467,929
Total	3,011,375	2,977,460
Other commercial | Special Mention
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	19,564
Term loans originated fiscal year before current fiscal year	0	12,582
Term loans originated two years before current fiscal year	0	0
Term loans originated three years before current fiscal year	0	0
Term loans originated four years before current fiscal year	0	0
Term loans originated five years before current fiscal year	0	0
Revolving loans	0	54
Total	0	32,200
Other commercial | Substandard
Credit Quality Indicators By Origination
Term loans originated current fiscal year	4	5,784
Term loans originated fiscal year before current fiscal year	26,289	6,864
Term loans originated two years before current fiscal year	10,664	6,233
Term loans originated three years before current fiscal year	6,169	5,114
Term loans originated four years before current fiscal year	2,402	2,056
Term loans originated five years before current fiscal year	16,342	11,329
Revolving loans	26,762	7,112
Total	88,632	44,492
Other commercial | Doubtful/ Loss
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	1	3
Term loans originated two years before current fiscal year	3	1
Term loans originated three years before current fiscal year	1	92
Term loans originated four years before current fiscal year	3	5
Term loans originated five years before current fiscal year	551	546
Revolving loans	18	18
Total	$ 577	$ 665