Debt - Narrative (Details)		1 Months Ended	3 Months Ended		9 Months Ended			12 Months Ended
	Apr. 09, 2018 USD ($) $ / shares	Nov. 30, 2019 USD ($) director individual	Sep. 30, 2020 USD ($) director	Sep. 29, 2019 USD ($)	Sep. 30, 2020 USD ($) director	Sep. 30, 2019 USD ($)	Sep. 29, 2019 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility
Interest expense			$ 58,063,000	$ 10,030,000	$ 173,890,000		$ 30,376,000
Loss on early extinguishment of debt			476,000	$ 0	1,650,000		$ 0
Current portion of long-term debt			15,179,000		15,179,000			$ 3,300,000
Senior secured term loan | Apollo Term Loan
Line of Credit Facility
Debt term (in years)		5 years
Aggregate principal amount		$ 1,800,000,000	$ 1,729,000,000		$ 1,729,000,000
Interest rate (as a percent)		11.50%			12.90%
Effective interest rate (as a percent)		6.50%
Number of Individuals | individual		2
Number of directors | director			1		1
Interest rate increase if gross leverage ratio exceeds certain thresholds (as a percent)		2.00%
Unrestricted cash requirement			$ 20,000,000		$ 20,000,000
Unrestricted cash prepaid requirement			40,000,000		$ 40,000,000
EBITDA initial ratio					1.00
Covenant, percent of net proceeds of asset sales (as a percent)					100.00%
Debt issuance costs		$ 4,900,000	4,100,000		$ 4,100,000
Unamortized discount		$ 116,600,000
Capitalized lender fees			93,300,000		93,300,000
Interest expense			51,000,000.0		152,400,000
Amortization of deferred financing costs			5,900,000		17,700,000
Loss on early extinguishment of debt			500,000		1,700,000
Interest paid			51,000,000.0			$ 176,000,000.0
Current portion of long-term debt			$ 15,200,000		$ 15,200,000
Senior secured term loan | Apollo Term Loan | Period 1
Line of Credit Facility
Covenant, percent of excess cash flow (as a percent)					50.00%
Senior secured term loan | Apollo Term Loan | Period 2
Line of Credit Facility
Covenant, percent of excess cash flow (as a percent)					90.00%
Senior secured term loan | Apollo Term Loan | Maximum
Line of Credit Facility
Number of directors | director		2
Convertible debt | Convertible senior notes
Line of Credit Facility
Aggregate principal amount	$ 201,300,000
Effective interest rate (as a percent)			6.05%		6.05%
Stated interest rate (as a percent)	4.75%
Proceeds from debt	$ 195,300,000
Stated conversion rate	0.0824572
Conversion price (in usd per share) | $ / shares	$ 12.13
Redemption value								$ 198,000,000.0
Convertible debt, principal			$ 3,300,000		$ 3,300,000