Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Source	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Significant Of Accounting Policies [Line Items]
Cash and cash equivalent maturity period			90 days
Amount due to customers under credit arrangements	$ 4,400,000		$ 4,400,000		$ 3,400,000
Minimum maturity for short-term investment			90 days
Maximum maturity for short-term investment			1 year
Number of primary sources | Source			2
Goodwill impairment			$ 0
Estimated dividend yield	0.00%		0.00%
Risk-free interest rate	1.99%		1.58%
Awards vesting, service period			4 years
Options expiration period			10 years
Foreign currency gains (losses)	$ (1,500,000)	$ (600,000)	$ (2,300,000)	$ (100,000)
Non-monetary transaction revenue totaled	1,100,000	400,000	4,400,000	1,300,000
Non-monetary transaction expense totaled	$ 700,000	$ 400,000	$ 4,600,000	$ 1,300,000
US Treasury [Member]
Significant Of Accounting Policies [Line Items]
Risk-free interest rate			0.00%
Software Development [Member]
Significant Of Accounting Policies [Line Items]
Estimated useful life			3 years