Fair Value Measurements Derivative Instruments - Additional Information (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014 interest_rate_swap_agreements
Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Number of Instruments Held	8
Derivative, Notional Amount	$ 5,750.0
Interest Rate Cap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	4,664.1
Derivative, Cap Interest Rate	4.50%
Interest Rate Cap [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 501.4
Derivative, Cap Interest Rate	7.00%