Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Loss Contingencies [Line Items]
Rent expense under cancelable and non-cancelable operating leases	$ 1.0	$ 1.1	$ 2.9	$ 2.8
Deposits as collateral for outstanding surety bonds	0.0		0.0		$ 0.5
Outstanding performance and surety bonds	195.9		195.9
Non-refundable deposits	55.6		55.6
Remaining purchase price of land	447.3		447.3
Project construction commitment
Loss Contingencies [Line Items]
Other commitment	$ 238.5		$ 238.5