Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease of cash outflow from financing activities	$ 148,501	$ (20,990)
Increase of cash outflow from operating activities	$ 5,103	(21,711)
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease of cash outflow from financing activities		1,000
Increase of cash outflow from operating activities		$ 1,000