Subsequent Event - Additional Information (Detail) (Acquisition, USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Oct. 03, 2011	Sep. 30, 2011
Subsequent Event [Line Items]
Acquisition consideration paid total cash consideration	$ 364
Acquisition transaction paid in shares	5,900,000
Acquisition transaction terms	Under the terms of the transaction, S1 stockholders can elect to receive $10.00 in cash or 0.3148 shares of the Company’s stock for each S1 share they own, subject to proration, such that in the aggregate 33.8% of S1 shares are exchanged for the Company’s shares and 66.2% are exchanged for cash.
Acquisition transaction, cash exchanged per S1 share	$ 10.00
Acquisition transaction, Company's stock exchanged per S1 share	0.3148
Proration of exchange percentage, S1 share for the Company's shares	33.80%
Proration of exchange percentage, S1 share for cash	66.20%
Business acquisition, available cash and cash equivalents to be used for purchase	90
Business acquisition cost of acquired entity purchase price per share		$ 9.55
Maximum
Subsequent Event [Line Items]
Increase in amount of borrowed funds	75
New Senior Secured Credit Facilities
Subsequent Event [Line Items]
Acquisition consideration amount borrowed	450
New Senior Secured Term Loan
Subsequent Event [Line Items]
Acquisition consideration amount borrowed	200
New Senior Secured Revolving Credit Facility
Subsequent Event [Line Items]
Acquisition consideration amount borrowed	$ 250