Summary of Changes in Allowance For Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Balance at beginning of year	$ 510	$ 210
Additions to expense	426	473	74
Writeoffs, net of recoveries and other adjustments	(213)	(173)
Balance at end of year	$ 723	$ 510	$ 210