Goodwill and Acquired Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Asset (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Beginning of year	$ 7,454	$ 718	$ 1,501
Acquired CDI	2,564	7,769	0
Amortization expense	(1,424)	(1,033)	(783)
End of year	$ 8,594	$ 7,454	$ 718