Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Other non-current assets, net	$ 18,417	$ 18,500	$ 18,704
Long-term debt	1,279,473	1,278,700	1,276,488
Deferred income tax assets (current)		0	0
Deferred income tax liabilities (noncurrent)	$ 269,469	272,100	288,251
Scenario, Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Other non-current assets, net		39,800	42,200
Long-term debt		1,300,000	1,300,000
Deferred income tax assets (current)		35,500	30,900
Deferred income tax liabilities (noncurrent)		307,600	319,100
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Other non-current assets, net		(21,300)	(23,500)
Long-term debt		(21,300)	(23,500)
Deferred income tax assets (current)		(35,500)	(30,900)
Deferred income tax liabilities (noncurrent)		$ (35,500)	$ (30,900)