Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Carrying value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value and fair value of notes payable and convertible notes payable	$ 2,007,242	$ 1,813,439
Fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value and fair value of notes payable and convertible notes payable	$ 2,007,229	$ 1,813,439