Significant Components of Contract Acquisition Costs (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Conversion costs, accumulated amortization	$ 140.8	$ 138.7
Payments for processing rights, accumulated amortization	$ 138.7	$ 137.4