CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 6,517	$ 9,675	$ 3,324	$ 3,787	$ 5,048	$ 2,762	$ 2,942	$ 2,626	$ 3,006	$ 2,659	$ 1,267	$ 1,462	$ 23,303	$ 13,378	$ 8,394
Other comprehensive income (loss):
Unrealized holding gains (losses) on securities arising during the period													(6,697)	(3,746)	4,198
Other comprehensive income (loss) before tax													(6,697)	(3,746)	4,198
Income tax (expense) benefit related to items of other comprehensive income													2,122	1,542	(1,728)
Other comprehensive income (loss)													(4,575)	(2,204)	2,470
Less: Reclassification adjustment for gains (loss) included in net earnings													1,043
Income tax (expense) benefit related to reclassification adjustment													(409)
Reclassification adjustment for gains included in net earnings, net of tax													634
Other comprehensive income (loss), net of tax													(3,941)	(2,204)	2,470
Total comprehensive income													$ 19,362	$ 11,174	$ 10,864