Shareholders' Deficit - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period	$ (102,072)	$ (130,446)
Income tax expense related to items of other comprehensive income		(1,146)
Balance as of end of period	(99,423)	(99,423)
Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period		(978)
Reclassification		80
Income tax expense related to items of other comprehensive income		(21)
Balance as of end of period	(919)	(919)
Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period		(59,427)
Reclassification		2,000
Changes in the fair value of cash flow derivatives		2,225
Income tax expense related to items of other comprehensive income		(1,125)
Balance as of end of period	(56,161)	(56,161)
Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification		166
Estimated reclassification from other comprehensive loss to interest expense related to the interest rate swaps over the next 12 months		100
Accumulated Other Comprehensive Loss, Net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period	(57,330)	(60,405)
Balance as of end of period	$ (57,080)	$ (57,080)