Organization and Basis of Presentation Development Fee Contracts (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Development Fee Contracts [Abstract]
Loss Contingency Accrual	$ 66,100,000		$ 66,100,000
Profit (loss) on development fee contracts	$ (60,000,000)	$ 431,000	$ (61,700,000)	$ 912,000