Loans Receivable, Net - Credit Quality Indicators for RRE and Consumer Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Credit Quality Indicators By Origination
Total	$ 11,618,731	$ 9,512,810
Residential Real Estate
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	141,655
Term loans originated in 2019	228,558
Term loans originated in 2018	129,077
Term loans originated in 2017	92,899
Term loans originated in 2016	65,216
Term loans originated in 2015 and prior	202,810
Revolving loans	2,399
Total	862,614	926,388
Residential Real Estate | Performing
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	141,655
Term loans originated in 2019	228,558
Term loans originated in 2018	128,043
Term loans originated in 2017	92,899
Term loans originated in 2016	64,382
Term loans originated in 2015 and prior	198,787
Revolving loans	2,399
Total	856,723
Residential Real Estate | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	0
Term loans originated in 2019	0
Term loans originated in 2018	791
Term loans originated in 2017	0
Term loans originated in 2016	0
Term loans originated in 2015 and prior	1,395
Revolving loans	0
Total	2,186
Residential Real Estate | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	0
Term loans originated in 2019	0
Term loans originated in 2018	243
Term loans originated in 2017	0
Term loans originated in 2016	834
Term loans originated in 2015 and prior	2,628
Revolving loans	0
Total	3,705
Home Equity
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	75
Term loans originated in 2019	1,028
Term loans originated in 2018	1,862
Term loans originated in 2017	1,745
Term loans originated in 2016	1,047
Term loans originated in 2015 and prior	17,337
Revolving loans	623,756
Total	646,850	617,201
Home Equity | Performing
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	75
Term loans originated in 2019	992
Term loans originated in 2018	1,861
Term loans originated in 2017	1,745
Term loans originated in 2016	1,047
Term loans originated in 2015 and prior	15,599
Revolving loans	619,423
Total	640,742
Home Equity | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	0
Term loans originated in 2019	0
Term loans originated in 2018	0
Term loans originated in 2017	0
Term loans originated in 2016	0
Term loans originated in 2015 and prior	1,059
Revolving loans	2,078
Total	3,137
Home Equity | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	0
Term loans originated in 2019	36
Term loans originated in 2018	1
Term loans originated in 2017	0
Term loans originated in 2016	0
Term loans originated in 2015 and prior	679
Revolving loans	2,255
Total	2,971
Other Consumer
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	106,569
Term loans originated in 2019	75,743
Term loans originated in 2018	49,929
Term loans originated in 2017	21,930
Term loans originated in 2016	12,424
Term loans originated in 2015 and prior	22,250
Revolving loans	25,283
Total	314,128	$ 295,660
Other Consumer | Performing
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	106,501
Term loans originated in 2019	75,340
Term loans originated in 2018	49,737
Term loans originated in 2017	21,829
Term loans originated in 2016	12,278
Term loans originated in 2015 and prior	21,106
Revolving loans	25,261
Total	312,052
Other Consumer | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	56
Term loans originated in 2019	354
Term loans originated in 2018	144
Term loans originated in 2017	62
Term loans originated in 2016	80
Term loans originated in 2015 and prior	932
Revolving loans	19
Total	1,647
Other Consumer | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated in 2020 (year-to-date)	12
Term loans originated in 2019	49
Term loans originated in 2018	48
Term loans originated in 2017	39
Term loans originated in 2016	66
Term loans originated in 2015 and prior	212
Revolving loans	3
Total	$ 429