Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 78,845		$ 78,845
Operating lease liability	83,882		$ 83,882
Discount rate, present value of future revenue			10.00%
Impairment charges		$ 0
Capitalized general and administrative costs	8,400	6,800	$ 16,800	$ 14,100
Interest costs capitalized	$ 2,600	$ 2,600	$ 4,200	$ 4,500
Restricted Stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Antidilutive securities (in shares)	2.8		2.8
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 62,300		$ 62,300
Operating lease liability	$ 62,300		$ 62,300