Long-Term Incentive Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2015	Apr. 30, 2008	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Long-Term Incentive Plan
Number of common shares reserved for issuance under LTIP (in shares)			12,050,000
Number of shares available for future issuance (in shares)			6,191,380
Amortization related to shares issued to design and construction employees			$ 580	$ 474	$ 393
Vesting of restricted stock presented on statement of equity			2,847	6,695	5,251
Amortization of deferred stock compensation			$ 6,536	$ 6,221	$ 4,858
Non-vested stock grants, number of shares
Outstanding at the beginning of the period (in shares)	1,883,296		1,883,296	2,009,412	1,539,992
Granted (in shares)			499,787	691,182	975,711
Vested (in shares)			(1,225,443)	(799,845)	(497,199)
Forfeited (in shares)			(171,295)	(17,453)	(9,092)
Outstanding at the end of the period (in shares)			986,345	1,883,296	2,009,412
Non-vested stock grants, weighted average price
Outstanding at the beginning of the period (in dollars per share)	$ 11.24		$ 11.24	$ 10.23	$ 9.11
Granted (in dollars per share)			17.33	13.48	11.82
Vested (in dollars per share)			10.75	10.61	9.89
Forfeited (in dollars per share)			14.76	11.90	10.89
Outstanding at the end of the period (in dollars per share)			$ 14.33	$ 11.24	$ 10.23
Restricted Shares and Performance awards
Long-Term Incentive Plan
Compensation Expense, including forfeitures			$ 9,695	$ 9,063	$ 7,189
Net-settle adjustment			(7,428)	(2,842)	(2,331)
Amortization related to shares issued to design and construction employees			580	474	393
Vesting of restricted stock presented on statement of equity			$ 2,847	$ 6,695	$ 5,251
Restricted Shares and Performance awards | Minimum
Long-Term Incentive Plan
Vesting period			3 years
Restricted Shares and Performance awards | Maximum
Long-Term Incentive Plan
Vesting period			5 years
Restricted Shares and Performance awards | Former Chief Executive Officer
Long-Term Incentive Plan
Compensation Expense, including forfeitures	$ 2,500
Amortization of deferred stock compensation	$ 1,600
Stock Options | Former Chairman
Stock options
Number of nonqualified stock options approved by the compensation committee of the Company's board of directors (in shares)		200,000
Exercise price of options vested (in dollars per share)		$ 17.71
Deferred shares, share purchase rights, or share appreciation rights issued or outstanding under the LTIP
Non-vested stock grants, number of shares
Outstanding at the end of the period (in shares)			0