Stock-Based Compensation Plans - Summary of Stock Options Issued Pursuant to Stock Incentive Plans (Detail)	9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares
Number of Shares
Outstanding, Beginning Balance | shares	5,282,693
Granted | shares	2,055,514
Exercised | shares	(1,108,965)
Forfeited | shares	(365,286)
Expired | shares	(593)
Outstanding, Ending Balance | shares	5,863,363
Number of Shares Exercisable, Ending Balance | shares	3,285,184
Weighted-Average Exercise Price
Beginning Balance	$ 12.06
Granted	19.12
Exercised	10.42
Forfeited	19.08
Expired	20.51
Ending Balance	14.41
Weighted-Average Exercise Price Exercisable, Ending Balance	$ 10.85
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding as of end of period	6 years 6 months 11 days
Weighted-Average Remaining Contractual Term (Years), Exercisable as of end of period	4 years 8 months 5 days
Aggregate Intrinsic Value of In-the-Money Options
Aggregate Intrinsic Value of In-the-Money Options, Outstanding as of end of period | $	$ 39,394,952
Aggregate Intrinsic Value of In-the-Money Options, Exercisable as of end of period | $	$ 33,735,724
Online Resources Corporation [Member]
Number of Shares
Outstanding, Beginning Balance | shares	46,512
Exercised | shares	(240)
Expired | shares	(8,187)
Outstanding, Ending Balance | shares	38,085
Number of Shares Exercisable, Ending Balance | shares	38,085
Weighted-Average Exercise Price
Beginning Balance	$ 36.73
Exercised	13.92
Expired	45.07
Ending Balance	35.09
Weighted-Average Exercise Price Exercisable, Ending Balance	$ 35.09
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding as of end of period	1 year 2 months 5 days
Weighted-Average Remaining Contractual Term (Years), Exercisable as of end of period	1 year 2 months 5 days
Aggregate Intrinsic Value of In-the-Money Options
Aggregate Intrinsic Value of In-the-Money Options, Outstanding as of end of period | $	$ 48,319
Aggregate Intrinsic Value of In-the-Money Options, Exercisable as of end of period | $	$ 48,319