Segment and Related Information - Reconciliation of the Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment and Related Information
Income from operations	$ 72,671	$ 71,907	$ 65,428
Interest expense, net	28,864	32,445	34,258
Non-service defined benefit plan expense	667	632	691
Income before income taxes	43,140	38,830	30,479
Provision for income taxes	1,158	638	2,954
Net income	41,982	38,192	27,525
Net revenues	1,120,488	1,001,150	1,098,046
Consolidated material costs	354,342	315,410	357,771
Property, plant and equipment	22,579	24,500	26,433
Total consolidated purchase of property, plant and equipment and therapeutic program equipment leased to third parties under operating leases	24,859	28,092	33,105
Total consolidated assets	998,139	950,751
Corporate & other
Segment and Related Information
Income from operations	(88,521)	(93,015)	(94,113)
Net revenues	0	0	0
Consolidated material costs	0	0	0
Total consolidated purchase of property, plant and equipment and therapeutic program equipment leased to third parties under operating leases	3,122	2,853	7,963
Total consolidated assets	159,450	250,868
Consolidating adjustments
Segment and Related Information
Net revenues	(220,792)	(189,604)	(203,496)
Consolidated material costs	(220,792)	(189,604)	(203,496)
Patient Care
Segment and Related Information
Income from operations	143,977	147,197	141,576
Net revenues	943,328	831,603	905,691
Consolidated material costs	287,204	247,384	274,801
Property, plant and equipment	10,242	10,607	16,102
Therapeutic program equipment leased to third parties under operating leases	0	0	0
Total consolidated purchase of property, plant and equipment and therapeutic program equipment leased to third parties under operating leases	10,242	10,607	16,102
Total consolidated assets	705,614	578,319
Products & Services
Segment and Related Information
Income from operations	17,215	17,725	17,965
Net revenues	397,952	359,151	395,851
Consolidated material costs	287,930	257,630	286,466
Property, plant and equipment	9,215	11,040	2,368
Therapeutic program equipment leased to third parties under operating leases	2,280	3,592	$ 6,672
Total consolidated assets	$ 133,075	$ 121,564