Fair Value Measurements - Financial Instruments Required to be Carried at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Liabilities
Contingent consideration	$ (2,927)	$ (2,957)
Level 1
Liabilities
Contingent consideration	0	0
Level 2
Liabilities
Contingent consideration	0	0
Level 3
Liabilities
Contingent consideration	(2,927)	(2,957)
Interest rate cap contracts
Assets
Interest rate derivatives	854	659
Interest rate cap contracts | Level 1
Assets
Interest rate derivatives	0	0
Interest rate cap contracts | Level 2
Assets
Interest rate derivatives	854	659
Interest rate cap contracts | Level 3
Assets
Interest rate derivatives	0	0
Interest rate swap agreements
Liabilities
Swap agreements	(3,847)	(5,232)
Interest rate swap agreements | Level 1
Liabilities
Swap agreements	0	0
Interest rate swap agreements | Level 2
Liabilities
Swap agreements	(3,847)	(5,232)
Interest rate swap agreements | Level 3
Liabilities
Swap agreements	0	0
Cross-currency swap agreements
Assets
Interest rate derivatives		11,578
Liabilities
Swap agreements	(5,340)
Cross-currency swap agreements | Level 1
Assets
Interest rate derivatives		0
Liabilities
Swap agreements	0
Cross-currency swap agreements | Level 2
Assets
Interest rate derivatives		11,578
Liabilities
Swap agreements	(5,340)
Cross-currency swap agreements | Level 3
Assets
Interest rate derivatives		$ 0
Liabilities
Swap agreements	$ 0