Commitments and Contingencies (Details)			1 Months Ended	3 Months Ended
	Sep. 12, 2017 USD ($)	Jun. 02, 2016 USD ($) Guarantee Entitiy	Mar. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2015 USD ($)	Sep. 04, 2015 USD ($)	Oct. 09, 2012 USD ($)
Commitments and Contingencies [Line Items]
Bank loan issued to VIE, partially guaranteed by parent		$ 46,200,000					$ 13,300,000	$ 18,000,000.0
Bank loan issued to VIE, percentage guaranteed by parent (percent)								25.00%
Parent's guarantor obligation, maximum exposure		$ 3,250,000					$ 1,800,000	$ 4,500,000.0
Number of variable interest entities obtaining debt | Entitiy		1
Number of guarantees | Guarantee		3
Transfer of notes receivable to third party	$ 24,200,000			$ 200,000
Notes receivable outstanding			$ 95,540,000	95,540,000	$ 93,392,000
Other commitment						$ 3,800,000
Construction loan			34,900,000	34,900,000
Additional capital contribution, commitment			14,400,000
Forgivable Notes Receivable
Commitments and Contingencies [Line Items]
Other commitment			215,100,000	215,100,000
Capital contributions to joint ventures
Commitments and Contingencies [Line Items]
Other commitment			13,500,000	13,500,000
Medium-term Notes | Variable Interest Entity, Not Primary Beneficiary
Commitments and Contingencies [Line Items]
Term loan obtained for refinancing for construction loan		$ 61,000,000
Notes Receivable
Commitments and Contingencies [Line Items]
Notes receivable outstanding	$ 49,100,000		$ 24,400,000	$ 24,400,000