Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended					9 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accounting Policies [Abstract]
Restricted cash		$ 2,200,000				$ 2,200,000		$ 1,600,000
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense		3,294,000			$ 85,000	$ 9,668,000	$ 10,524,000
Accounting Standards Update 2015-17
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Current deferred tax asset								5,100,000
Non-current deferred tax liabilities								$ 13,900,000
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense		$ 0	$ 0	$ 500,000
Forecast | Minimum | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	$ 600,000
Forecast | Maximum | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	$ 900,000