Taxes on Income - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Unrealized losses on available-for-sale securities	$ 2,084	$ 4,170
Allowance for loan losses	8,526	13,913
Purchase accounting adjustments—loans	3,487	8,339
Reserves and other accruals	9,194	14,010
Provision for legal settlement	2,520	0
Deferred gains	589	1,109
Net operating losses	188	352
Derivatives	757	1,086
Reverse mortgages	606	2,262
Total deferred tax assets	27,951	45,241
Deferred tax liabilities:
Bad debt recapture	0	(545)
Accelerated depreciation	(778)	(1,049)
Other	(326)	(497)
Bank-owned life insurance	(5,387)	0
Deferred loan costs	(989)	(1,079)
Intangibles	(3,826)	(5,946)
Total deferred tax liabilities	(11,306)	(9,116)
Net deferred tax asset	$ 16,645	$ 36,125