Long-Term Incentive Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 31, 2015	Apr. 30, 2008	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Long-Term Incentive Plan
Amortization related to shares issued to design and construction employees					$ 450	$ 442
Former Chief Executive Officer
Long-Term Incentive Plan
Amortization Expense, including forfeitures	$ 2,500
Restricted Shares and Performance awards
Long-Term Incentive Plan
Amortization Expense, including forfeitures			$ 1,539	$ 1,262	5,616	8,106
Amortization related to shares issued to design and construction employees				$ 100	$ 500	$ 400
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
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 outstanding options (in dollars per share)			$ 17.71		$ 17.71