Significant Accounting Policies (Details 8) In Millions, unless otherwise specified	Sep. 30, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2013 Interest rate swap USD ($) instrument	Dec. 31, 2012 Interest rate swap USD ($)	Sep. 30, 2013 Interest rate cap USD ($) instrument	Sep. 30, 2013 USD-Yen currency forward contract USD ($)	Sep. 30, 2013 USD-Yen currency forward contract JPY (¥)
Derivative financial instruments
Number of Instruments			2		5
Notional Amount			$ 492.2		$ 249.4		¥ 1,700.0
Interest rate net derivative liability, fair value			4.6	1.5
Asset value of forwards included in deferred costs and other assets						4.1
Gross accumulated other comprehensive income or loss related to derivative activities	$ 70.6	$ 78.1