Loans Receivable, Net - Credit Grades and Risk Characteristics (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 413,599
2019	1,506,439
2018	1,080,978
2017	966,010
2016	748,449
2015 and prior	2,882,253
Revolving lines of credit	334,862
Total	7,932,590	$ 6,214,652
Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	8,118
2019	61,109
2018	64,241
2017	49,781
2016	47,835
2015 and prior	119,314
Revolving lines of credit	152,362
Total	502,760
Commercial real estate – owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2020	59,276
2019	156,574
2018	138,786
2017	146,916
2016	140,063
2015 and prior	556,502
Revolving lines of credit	22,866
Total	1,220,983
Commercial real estate – investor
Financing Receivable, Credit Quality Indicator [Line Items]
2020	200,651
2019	663,009
2018	410,844
2017	514,110
2016	356,544
2015 and prior	1,029,384
Revolving lines of credit	157,120
Total	3,331,662
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,877,185	2,729,155
Pass | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	7,718
2019	61,109
2018	60,217
2017	47,452
2016	47,051
2015 and prior	111,383
Revolving lines of credit	147,529
Total	482,459
Pass | Commercial real estate – owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2020	59,276
2019	154,245
2018	138,376
2017	143,086
2016	136,276
2015 and prior	531,105
Revolving lines of credit	22,560
Total	1,184,924
Pass | Commercial real estate – investor
Financing Receivable, Credit Quality Indicator [Line Items]
2020	200,651
2019	662,802
2018	410,180
2017	511,079
2016	345,525
2015 and prior	983,984
Revolving lines of credit	144,341
Total	3,258,562
Special Mention | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	112
2017	832
2016	712
2015 and prior	54
Revolving lines of credit	800
Total	2,510
Special Mention | Commercial real estate – owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	191
2018	0
2017	1,399
2016	1,396
2015 and prior	1,439
Revolving lines of credit	306
Total	4,731
Special Mention | Commercial real estate – investor
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	29
2018	0
2017	3,031
2016	5,950
2015 and prior	19,709
Revolving lines of credit	8,768
Total	37,487
Substandard | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	400
2019	0
2018	3,912
2017	1,497
2016	72
2015 and prior	7,877
Revolving lines of credit	4,033
Total	17,791
Substandard | Commercial real estate – owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	2,138
2018	410
2017	2,431
2016	2,391
2015 and prior	23,958
Revolving lines of credit	0
Total	31,328
Substandard | Commercial real estate – investor
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	178
2018	664
2017	0
2016	5,069
2015 and prior	25,691
Revolving lines of credit	4,011
Total	35,613
Residential real estate | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	138,889
2019	588,723
2018	347,761
2017	220,845
2016	182,685
2015 and prior	979,738
Revolving lines of credit	0
Total	2,458,641	$ 2,321,157
Residential real estate | Pass | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	138,889
2019	588,723
2018	347,761
2017	220,624
2016	182,541
2015 and prior	976,664
Revolving lines of credit	0
Total	2,455,202
Residential real estate | Special Mention | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	221
2016	144
2015 and prior	3,074
Revolving lines of credit	0
Total	3,439
Residential real estate | Substandard | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015 and prior	0
Revolving lines of credit	0
Total	0
Home Equity Lines and Other Consumer Loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,665
2019	37,024
2018	119,346
2017	34,358
2016	21,322
2015 and prior	197,315
Revolving lines of credit	2,514
Total	418,544
Home Equity Lines and Other Consumer Loans | Pass | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,665
2019	37,024
2018	119,311
2017	34,358
2016	21,322
2015 and prior	194,187
Revolving lines of credit	2,514
Total	415,381
Home Equity Lines and Other Consumer Loans | Special Mention | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015 and prior	530
Revolving lines of credit	0
Total	530
Home Equity Lines and Other Consumer Loans | Substandard | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	35
2017	0
2016	0
2015 and prior	2,598
Revolving lines of credit	0
Total	$ 2,633