Property and Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property and Equipment
Depreciation expense	$ 411.9	$ 353.4	$ 286.0
Capital Leases, Balance Sheet, Assets by Major Class, Net	$ 868.3	$ 790.5