Summary of Significant Accounting Policies - Reclassifications and New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities			$ 120,517	$ 97,905
Net cash provided by financing activities			$ 341,042	$ 122,373
Adjustments for New Accounting Principle, Early Adoption [Member] | Accounting Standards Update 2016-15 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities	$ 800	$ 2,000
Net cash provided by financing activities	$ (800)	$ (2,000)