Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated deficit		$ (4,586,856)	$ (4,931,210)
Deferred tax assets		$ 910,510	$ 1,115,731
Early Adoption, Effect | Forecast
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated deficit	$ 300,000
Deferred tax assets	$ 300,000