Fair Value of Financial Instruments (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Jun. 30, 2014
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible notes, fair value	$ 326,000,000	$ 198,000,000
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of debt issued	$ 200,000,000	$ 200,000,000	$ 200,000,000.0