Acquisition - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Business Acquisition [Line Items]
Aggregate business acquisition purchase price	$ 37,827				$ 37,827
Revenue		64,964	63,507	128,362	117,158
Net income		18,191	19,343	35,666	34,669
Xtrakter Limited [Member]
Business Acquisition [Line Items]
Revenue					7,400
Net income					$ 300