Goodwill and Other Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Gross carrying amount at beginning of year	$ 16,401	$ 16,401
Additions	5,713	0
Accumulated amortization	(15,589)	(13,770)
Gross carrying amount at end of year	$ 6,525	$ 2,631