Summary of Significant Accounting Policies - Newly Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets	$ 177,293	$ 180,600
Present value of lease liabilities	178,514
Straight-line rent liability	$ 5,100
Prepaid rent		4,900
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets		175,700
Present value of lease liabilities		$ 181,600