Long-term Debt - Senior Notes (Details) (Propco [Member], USD $) In Millions, unless otherwise specified				9 Months Ended							9 Months Ended
	Jun. 18, 2011 Term Loan Facility [Member]	Jan. 03, 2012 Tranche B-3 [Member]	Jun. 18, 2011 Tranche B-3 [Member]	Sep. 30, 2012 Senior Notes [Member]	Jun. 16, 2017 Senior Notes [Member]	Jun. 16, 2016 Senior Notes [Member]	Jun. 16, 2014 Senior Notes [Member]	Jun. 16, 2013 Senior Notes [Member]	Jun. 16, 2012 Senior Notes [Member]	Jan. 03, 2012 Senior Notes [Member]	Sep. 30, 2012 Subsequent Event [Member] Senior Notes [Member]	Sep. 30, 2012 Minimum [Member] Subsequent Event [Member] Senior Notes [Member]	Sep. 30, 2012 Maximum [Member] Subsequent Event [Member] Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 1,575.0	$ 625.0	$ 625.0							$ 625.0
Debt Instrument, effective interest rate percentage					9.54%	7.22%	4.87%	3.67%	3.66%	3.65%
Debt instrument, duration fee (percentage)				1.00%
Debt instrument, notification for redemption (term)												30 days	60 days
Redemption price of debt instrument, principal (percentage)											100.00%
Debt instrument, requirement to repurchase principal (percentage)				100.00%