Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Information
Total interest income	$ 29,038	$ 19,007
Total interest expense	8,930	5,476
Net interest income	20,108	13,531
Provision for loan losses	1,406	240
Net Interest Income After Provision for Loan Losses	18,702	13,291
Total noninterest income	11,313	8,091
Noninterest expense	10,270	6,641
Income Before Income Taxes	19,745	14,741
Income Tax Expense (Benefit)	4,684	5,611
Net Income	15,061	9,130
Total assets	3,675,849	2,800,681	$ 3,393,133
Other
Segment Information
Total interest income	265
Total interest expense	(460)	(86)
Net interest income	725	86
Net Interest Income After Provision for Loan Losses	725	86
Total noninterest income	(336)
Noninterest expense	1,983	1,047
Income Before Income Taxes	(1,594)	(961)
Income Tax Expense (Benefit)	(561)	(366)
Net Income	(1,033)	(595)
Total assets	21,739	10,509
Multifamily | Operating Segments
Segment Information
Total interest income	163	51
Net interest income	163	51
Net Interest Income After Provision for Loan Losses	163	51
Total noninterest income	10,511	7,223
Noninterest expense	3,382	1,595
Income Before Income Taxes	7,292	5,679
Income Tax Expense (Benefit)	1,808	2,162
Net Income	5,484	3,517
Total assets	141,703	104,709
Mortgage Warehousing | Operating Segments
Segment Information
Total interest income	11,857	10,149
Total interest expense	3,797	2,613
Net interest income	8,060	7,536
Provision for loan losses	674	247
Net Interest Income After Provision for Loan Losses	7,386	7,289
Total noninterest income	486	625
Noninterest expense	1,736	1,787
Income Before Income Taxes	6,136	6,127
Income Tax Expense (Benefit)	1,506	2,332
Net Income	4,630	3,795
Total assets	1,603,584	1,048,771
Banking | Operating Segments
Segment Information
Total interest income	16,753	8,807
Total interest expense	5,593	2,949
Net interest income	11,160	5,858
Provision for loan losses	732	(7)
Net Interest Income After Provision for Loan Losses	10,428	5,865
Total noninterest income	652	243
Noninterest expense	3,169	2,212
Income Before Income Taxes	7,911	3,896
Income Tax Expense (Benefit)	1,931	1,483
Net Income	5,980	2,413
Total assets	$ 1,908,823	$ 1,636,692