Supplementary Balance Sheet Information - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Cash and cash equivalents, money market accounts	$ 24,500,000		$ 24,500,000		$ 22,000,000
Amortization expense related to conversion costs	7,300,000	4,700,000	11,500,000	10,100,000
Amortization related to payments for processing rights	2,900,000	4,000,000	6,800,000	7,900,000
Impairment loss related to contract acquisition costs					$ 773,000
Maximum
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Cash and cash equivalents, money market accounts, original maturity date	90 days		90 days		90 days