Supplementary Balance Sheet Information - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Cash and cash equivalents, money market accounts	$ 32,000,000		$ 22,000,000
Amortization expense related to conversion costs	4,100,000	4,500,000
Amortization related to payments for processing rights	3,900,000	3,900,000
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