Debt - 2021 Notes (Details) - USD ($)				3 Months Ended		9 Months Ended
	Jun. 28, 2016	Jun. 10, 2016	Apr. 29, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Apr. 01, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Loss on extinguishment of debt				$ 0	$ 0	$ 5,116,000	$ 0
Debt instrument, carrying amount				$ 649,195,000		$ 649,195,000			$ 125,000,000
Notes Payable | 6.50% notes, due 2021
Debt Instrument [Line Items]
Debt instrument face amount								$ 320,000,000.0
Debt instrument, percentage rate				6.50%		6.50%		6.50%
Repurchased face amount	$ 560,000	$ 315,245,000
Percentage of principal amount repurchased		98.50%
Repurchased face amount per $1,000 principal amount	1,010	$ 1,015
Debt repurchase amount		320,000,000
Tender Offer premium		4,700,000				$ 4,700,000
Interest paid		$ 3,100,000
Loss on extinguishment of debt						5,100,000
Write off of unamortized purchase accounting adjustment						400,000
Interest payable				$ 100,000		100,000
Percentage of principal amount redeemed			101.00%
Repayments of debt	$ 600,000
Debt instrument, carrying amount				4,195,000		4,195,000			$ 0
Notes Payable | 6.50% notes, due 2021 | Level 2
Debt Instrument [Line Items]
Fair value of debt				$ 4,200,000		$ 4,200,000