Summary of Significant Accounting Policies - Accounting Pronouncements Adopted (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Recently Issued Accounting Pronouncements
Operating lease assets	$ 18,780
Operating lease liabilities	$ 30,401
ASU 2016 - 02 | Restatement Adjustment
Recently Issued Accounting Pronouncements
Operating lease assets		$ 4,000
Operating lease liabilities		$ 4,000