Significant Components of Contract Acquisition Costs, Net of Accumulated Amortization (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Acquired Finite-Lived Intangible Assets [Line Items]
Conversion costs, accumulated amortization	$ 91.9	$ 109.8
Payments for processing rights, accumulated amortization	$ 192.7	$ 186.1