Fair Value Measurements (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Oct. 31, 2013	Aug. 31, 2013
Derivatives Fair Value
Loss to be reclassified during next 12 months	$ 8,200,000		$ 8,200,000
Assets held for sale	14,500,000		14,500,000		$ 16,700,000
Interest rate swap
Derivatives Fair Value
Derivative notional amount						$ 200,000,000.0	$ 500,000,000.0
Derivative average fixed interest rate							2.151%
Basis spread on variable rate (as a percent)							1.00%
Gain (loss) on derivatives representing change in fair value of hedges	4,600,000	$ 5,600,000	3,600,000	$ 800,000
Reclassification of loss recognized in other comprehensive income (loss), effective portion	2,000,000		4,100,000
Derivative liability fair value	11,800,000		11,800,000		11,900,000
Accrued Liabilities | Interest rate swap
Derivatives Fair Value
Derivative liability fair value	8,200,000		8,200,000		7,900,000
Other long-term liabilities | Interest rate swap
Derivatives Fair Value
Derivative liability fair value	$ 3,600,000		$ 3,600,000		$ 4,000,000