Fair Value Measurements (Details) $ in Thousands	Sep. 30, 2016 USD ($) derivative	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Embedded derivative	$ (149,873)	$ (193,077)
Number of interest rate derivatives | derivative	0
Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Embedded derivative	$ (149,873)	(193,077)
Total net assets	(138,509)	(162,059)
Fair value of derivative instruments	11,364	31,018
Fair Value, Inputs, Level 2 | Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	11,364	31,018
Total net assets	11,364	31,018
Fair Value, Inputs, Level 3 | Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Embedded derivative	(149,873)	(193,077)
Total net assets	$ (149,873)	$ (193,077)