Significant Components of Contract Acquisition Costs, Net of Accumulated Amortization (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Conversion costs, accumulated amortization	$ 118.7	$ 105.4
Payments for processing rights, accumulated amortization	$ 120.3	$ 110.6