Chargeback Reserves (Details) (Chargeback Reserves [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Chargeback Reserves [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Chargeback liabilities, beginning Balance	$ 46.2	$ 42.5	$ 48.7
Add: Provisions	52.9	39.9	29.6
Deduct: Chargebacks	(43.1)	(36.2)	(35.8)
Chargeback liabilities, ending Balance	$ 56.0	$ 46.2	$ 42.5