Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Loans - Net Loans Held-for-Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Loans held-for-investment, net	$ 3,255,860	$ 3,245,170
Allowance for loan losses	(27,486)	(27,497)	$ (26,172)	$ (26,160)
Net loans held-for-investment	3,228,374	3,217,673
Originated
Loans and Leases Receivable Disclosure [Line Items]
Loans	40,259	45,623
Deferred loan cost, net	6,849	6,892
Loans held-for-investment, net	2,727,852	2,678,877
Allowance for loan losses	(26,476)	(26,487)	(25,218)	(25,172)
Purchased Credit-Impaired
Loans and Leases Receivable Disclosure [Line Items]
Loans held-for-investment, net	18,892	20,143
Allowance for loan losses	(1,010)	(1,010)	(951)	(951)
Acquired Loans
Loans and Leases Receivable Disclosure [Line Items]
Loans	509,116	546,150
Loans held-for-investment, net	509,116	546,150
Allowance for loan losses	0	0	(3)	(37)
Real Estate \| Originated
Loans and Leases Receivable Disclosure [Line Items]
Loans	2,680,744	2,626,362
Real Estate \| Originated \| Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Loans	1,978,070	1,930,535
Loans held-for-investment, net	1,981,444	1,933,946
Allowance for loan losses	(18,346)	(18,084)	(17,412)	(17,374)
Real Estate \| Originated \| Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans	502,294	499,311
Loans held-for-investment, net	502,849	499,860
Allowance for loan losses	(5,382)	(5,630)	(5,213)	(5,196)
Real Estate \| Originated \| One-to-Four Family
Loans and Leases Receivable Disclosure [Line Items]
Loans	90,825	91,371
Loans held-for-investment, net	91,873	92,433
Allowance for loan losses	(370)	(342)	(455)	(503)
Real Estate \| Originated \| Home equity and lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Loans	79,374	78,593
Loans held-for-investment, net	81,136	80,315
Allowance for loan losses	(336)	(291)	(225)	(122)
Real Estate \| Originated \| Construction and Land
Loans and Leases Receivable Disclosure [Line Items]
Loans	30,181	26,552
Loans held-for-investment, net	30,199	26,613
Allowance for loan losses	(574)	(463)	(463)	(610)
Real Estate \| Acquired Loans
Loans and Leases Receivable Disclosure [Line Items]
Loans	499,032	534,211
Real Estate \| Acquired Loans \| Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Loans	132,649	145,485
Real Estate \| Acquired Loans \| Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans	134,488	133,263
Real Estate \| Acquired Loans \| One-to-Four Family
Loans and Leases Receivable Disclosure [Line Items]
Loans	208,461	225,877
Real Estate \| Acquired Loans \| Home equity and lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Loans	15,292	17,583
Real Estate \| Acquired Loans \| Construction and Land
Loans and Leases Receivable Disclosure [Line Items]
Loans	8,142	12,003
Commercial and Industrial \| Originated
Loans and Leases Receivable Disclosure [Line Items]
Loans	38,924	44,104
Loans held-for-investment, net	39,016	44,190
Allowance for loan losses	(1,376)	(1,569)	(1,337)	(1,273)
Commercial and Industrial \| Acquired Loans
Loans and Leases Receivable Disclosure [Line Items]
Loans	10,083	11,933
Other \| Originated
Loans and Leases Receivable Disclosure [Line Items]
Loans	1,335	1,519
Loans held-for-investment, net	1,335	1,520
Allowance for loan losses	(92)	(108)	$ (113)	$ (94)
Other \| Acquired Loans
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 1	$ 6