Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	$ 6,653,826		$ 7,160,426	$ 7,294,019
Liabilities	3,776,776		$ 3,980,556
Proceeds from lease payments	$ 78,668
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		$ 4,507
Liabilities		$ 4,507