Shareholders' Deficit - Components of Accumulated Other Comprehensive Loss (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period	$ (130,446)
Income tax expense related to items of other comprehensive income	(1,059)
Balance as of end of period	(102,072)
Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period	(978)
Reclassification	40
Income tax expense related to items of other comprehensive income	(10)
Balance as of end of period	(948)
Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of period	(59,427)
Reclassification	995
Changes in the fair value of cash flow derivatives	2,978
Income tax expense related to items of other comprehensive income	(1,049)
Balance as of end of period	(56,382)
Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification	121
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	(60,405)
Balance as of end of period	$ (57,330)