Revenue From Contracts with Customers - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Time frame for majority of payments on health care plans and programs accounts (in days)	90 days
Bad debt expense	$ 2,021	$ 1,620
Deferred revenue	77,000
Previously deferred revenue recognized	$ 27,700	$ 25,900
Minimum
Disaggregation of Revenue [Line Items]
General payment terms for accounts on health care plans and programs (in days)	14 days
Unearned revenue, estimated delivery time for period end calculation (in days)	4 days
Maximum
Disaggregation of Revenue [Line Items]
General payment terms for accounts on health care plans and programs (in days)	120 days
Unearned revenue, estimated delivery time for period end calculation (in days)	10 days