Income Taxes - Summary of Changes in Valuation Allowance (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Valuation allowance at beginning of year	$ 7,743	$ 727	$ 287
Current year income	(101)	(65)	440
State net operating loss	(155)	(406)
Capital (loss) gain	(59)	7,487
Valuation allowance at end of year	$ 7,428	$ 7,743	$ 727