Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income taxes	$ 0	$ 0
Uncertain tax position	0			$ 0
Right of use asset - operating lease	4,412,000		$ 4,452,000
Operating lease, liability	$ 5,283,000
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right of use asset - operating lease			4,452,000
Operating lease, liability			$ 5,300,000