Long-Term Indebtedness (Details) (USD $)	3 Months Ended	1 Months Ended	3 Months Ended			1 Months Ended	3 Months Ended				0 Months Ended		1 Months Ended	3 Months Ended	12 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended			1 Months Ended	0 Months Ended	3 Months Ended		3 Months Ended							3 Months Ended	12 Months Ended		1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012 Interest rate contract	Mar. 31, 2013 Payable July 15, 2013	Mar. 31, 2013 Payable January 15, 2021	Dec. 20, 2011 New Credit Facility	Dec. 31, 2011 Revolving Loan	Mar. 31, 2013 Revolving Loan	Mar. 31, 2012 Revolving Loan	Dec. 31, 2012 Revolving Loan	Dec. 20, 2011 Revolving Loan	Dec. 21, 2012 New Term Loans	Dec. 21, 2012 Term Loan A	Dec. 31, 2011 Term Loan A	Mar. 31, 2013 Term Loan A	Dec. 31, 2012 Term Loan A	Dec. 21, 2012 Term Loan B	Dec. 31, 2011 Term Loan B	Mar. 31, 2013 Term Loan B	Dec. 31, 2012 Term Loan B	Mar. 31, 2012 Term Loan B	Dec. 31, 2011 First Lien Amendment	Dec. 21, 2012 Senior unsecured 2021 Notes	Mar. 31, 2013 Senior unsecured 2021 Notes	Dec. 31, 2012 Senior unsecured 2021 Notes	Mar. 31, 2013 HWP Refinance Loan item	Dec. 31, 2012 HWP Refinance Loan	Apr. 30, 2010 Exit Second Lien Facility	Apr. 30, 2010 Senior Credit Facility	Mar. 31, 2013 Revolving Loan	Dec. 31, 2012 Revolving Loan	Apr. 30, 2010 Exit First Lien Term Loan	Mar. 31, 2013 HWP HWP Refinance Loan	Dec. 31, 2012 HWP HWP Refinance Loan	Nov. 30, 2007 HWP HWP Refinance Loan	Nov. 30, 2007 HWP Construction term loan	Apr. 30, 2010 TW Borrowers TW Loan
Summary of Long-term debt
Maximum borrowing capacity of revolving loan					$ 1,135,000,000					$ 200,000,000																	$ 250,000,000	$ 890,000,000			$ 770,000,000					$ 150,000,000
Period of line of credit						5 years
Debt maturity period													5 years				7 years
Proceeds from Term Loans						935,000,000							75,000,000				860,000,000
Additional borrowing capacity																	300,000,000
Cash used to retire debt																					15,000,000
Repayment of debt												72,200,000				277,800,000					950,000,000														31,000,000
Debt instrument, additional borrowings amount																						800,000,000
Proceeds utilized for repayment of existing debt																						350,000,000
Remaining proceeds utilized for share repurchases and other corporate matters																						450,000,000
Reduction in interest rate (as a percent)																0.25%
Advances outstanding																													0	0
Letter of credit amount excluded from borrowing capacity							18,800,000		18,200,000																1,000,000
Debt instruments base rate		LIBOR					LIBOR							LIBOR	LIBOR			LIBOR
Unused commitment fee (as a percent)							0.50%	0.50%
Interest rate, variable interest rate floor (as a percent)																		1.00%
Increase in refinance loan																		580,732,000	582,187,000	470,000,000			800,000,000	800,000,000	31,010,000	31,128,000								33,000,000
Frequency of periodic payment of interest			Annual	Annual																			semi annual
Component of agreement for Term loan B		470,000,000
Derivative Cap (as a percent)		1.00%
Debt instrument, interest rate at period end (as a percent)																		4.00%	4.00%
Quarterly amortization																		1,500,000
Accrued interest on debt instrument (as a percent)																						5.25%										6.72%
Periodic payment of interest	21,000,000		22,300,000	21,000,000
Net loss on prepayment of debt											600,000
Monthly payments of principal and interest																																200,000
Amount deposited into escrow																																$ 1,100,000	$ 1,200,000
Period for release of limited guarantee																									5 years
Number of joint venture partners who provided guarantee of Refinance Loan in the event of specific default																									1