Income Taxes - Schedule of Reconciliation of Change in Federal and State Gross Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 1,902	$ 978	$ 200
Increase	55	924	0
Decrease	(1,673)	0	0
Current period tax positions	0	0	913
Reductions for statute of limitations expirations	0	0	(135)
Balance at End of Year	284	1,902	978
Amount That Would Affect the Effective Tax Rate if Recognized	$ 184	$ 148	$ 147