Loans Receivable, Net - Credit Quality Indicators for RRE and Consumer Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Credit Quality Indicators By Origination
Total	$ 11,293,891	$ 11,122,696
Residential real estate
Credit Quality Indicators By Origination
Term loans originated current fiscal year	256,012	208,679
Term loans originated fiscal year before current fiscal year	177,765	181,924
Term loans originated two years before current fiscal year	78,061	100,273
Term loans originated three years before current fiscal year	56,371	76,394
Term loans originated four years before current fiscal year	50,489	53,819
Term loans originated five years before current fiscal year	160,662	179,085
Revolving loans	2,178	2,334
Total	781,538	802,508
Residential real estate | Performing
Credit Quality Indicators By Origination
Term loans originated current fiscal year	256,012	207,432
Term loans originated fiscal year before current fiscal year	177,617	179,915
Term loans originated two years before current fiscal year	78,061	99,135
Term loans originated three years before current fiscal year	56,088	75,527
Term loans originated four years before current fiscal year	49,418	52,905
Term loans originated five years before current fiscal year	158,510	174,281
Revolving loans	2,178	2,334
Total	777,884	791,529
Residential real estate | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	1,247
Term loans originated fiscal year before current fiscal year	148	2,009
Term loans originated two years before current fiscal year	0	556
Term loans originated three years before current fiscal year	0	867
Term loans originated four years before current fiscal year	892	87
Term loans originated five years before current fiscal year	97	1,876
Revolving loans	0	0
Total	1,137	6,642
Residential real estate | Non-Accrual and 90 Days or More Past Due
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	582
Term loans originated three years before current fiscal year	283	0
Term loans originated four years before current fiscal year	179	827
Term loans originated five years before current fiscal year	2,055	2,928
Revolving loans	0	0
Total	2,517	4,337
Home equity
Credit Quality Indicators By Origination
Term loans originated current fiscal year	38	89
Term loans originated fiscal year before current fiscal year	67	807
Term loans originated two years before current fiscal year	589	1,782
Term loans originated three years before current fiscal year	887	1,452
Term loans originated four years before current fiscal year	783	1,016
Term loans originated five years before current fiscal year	10,780	14,025
Revolving loans	647,776	617,234
Total	660,920	636,405
Home equity | Performing
Credit Quality Indicators By Origination
Term loans originated current fiscal year	38	89
Term loans originated fiscal year before current fiscal year	67	771
Term loans originated two years before current fiscal year	555	1,782
Term loans originated three years before current fiscal year	887	1,426
Term loans originated four years before current fiscal year	783	1,016
Term loans originated five years before current fiscal year	10,114	13,042
Revolving loans	642,827	612,545
Total	655,271	630,671
Home equity | 30-89 Days Past Due
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	26
Term loans originated four years before current fiscal year	0	0
Term loans originated five years before current fiscal year	161	463
Revolving loans	2,933	2,397
Total	3,094	2,886
Home equity | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	0	36
Term loans originated two years before current fiscal year	34	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	505	520
Revolving loans	2,016	2,292
Total	2,555	2,848
Other consumer
Credit Quality Indicators By Origination
Term loans originated current fiscal year	127,963	131,302
Term loans originated fiscal year before current fiscal year	87,303	66,327
Term loans originated two years before current fiscal year	42,347	42,827
Term loans originated three years before current fiscal year	23,468	16,287
Term loans originated four years before current fiscal year	9,548	10,519
Term loans originated five years before current fiscal year	19,132	18,692
Revolving loans	30,487	27,117
Total	340,248	313,071
Other consumer | Performing
Credit Quality Indicators By Origination
Term loans originated current fiscal year	127,893	131,098
Term loans originated fiscal year before current fiscal year	87,072	65,921
Term loans originated two years before current fiscal year	41,943	42,557
Term loans originated three years before current fiscal year	23,180	16,202
Term loans originated four years before current fiscal year	9,495	10,409
Term loans originated five years before current fiscal year	16,871	17,334
Revolving loans	30,435	26,704
Total	336,889	310,225
Other consumer | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	65	158
Term loans originated fiscal year before current fiscal year	189	170
Term loans originated two years before current fiscal year	172	212
Term loans originated three years before current fiscal year	94	38
Term loans originated four years before current fiscal year	42	48
Term loans originated five years before current fiscal year	2,042	1,155
Revolving loans	34	411
Total	2,638	2,192
Other consumer | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	5	46
Term loans originated fiscal year before current fiscal year	42	236
Term loans originated two years before current fiscal year	232	58
Term loans originated three years before current fiscal year	194	47
Term loans originated four years before current fiscal year	11	62
Term loans originated five years before current fiscal year	219	203
Revolving loans	18	2
Total	$ 721	$ 654