Acquisitions - Fair Value of Assets and Liabilities Acquired (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	9 Months Ended	10 Months Ended	12 Months Ended
	Mar. 30, 2019	Mar. 30, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair value of identifiable assets and liabilities:
Goodwill				$ 602,500	$ 602,500	$ 602,500	$ 585,942	$ 549,063
Purchase price:
Cash consideration, net of cash acquired						57,799	167,688	131,448
Gain on previously held shares			$ 20,800			0	20,767	$ 0
Measurement Period Adjustment
Measurement period adjustments, Goodwill						(2,783)	(3,663)
VPI
Fair value of identifiable assets and liabilities:
Accounts receivable	$ 11,417	$ 11,417		10,997	10,997	10,997
Inventories	2,555	2,555		2,414	2,414	2,414
Other current assets	261	261		301	301	301
Property and equipment	3,166	3,166		3,342	3,342	3,342
Identifiable intangible assets	17,702	17,702		23,437	23,437	23,437
Operating lease assets	3,739	3,739		3,739	3,739	3,739
Goodwill	26,553	26,553		23,500	23,500	23,500
Other assets	10	10		10	10	10
Total assets	65,403	65,403		67,740	67,740	67,740
Accounts payable	2,629	2,629		2,629	2,629	2,629
Other current liabilities	1,875	1,875		2,397	2,397	2,397
Operating lease liability	3,413	3,413		3,413	3,413	3,413
Other liabilities	0	0		1,502	1,502	1,502
Total liabilities	7,917	7,917		9,941	9,941	$ 9,941
Purchase price:
Cash consideration, net of cash acquired		57,486			$ 57,799
Measurement Period Adjustment
Measurement period adjustments, Accounts receivable				(420)
Measurement period adjustments, Inventories				(141)
Measurement period adjustments, Other current assets				40
Measurement period adjustments, Property and equipment				176
Measurement period adjustments, Identifiable intangible assets				5,735
Measurement period adjustments, Goodwill				(3,053)
Measurement period adjustments, Total assets				2,337
Measurement period adjustments, Other current liabilities				522
Measurement period adjustments, Other liabilities				1,502
Measurement period adjustments, Total liabilities				2,024
Measurement period adjustments, Total consideration, net of cash acquired				$ 313
2018 Acquisitions
Fair value of identifiable assets and liabilities:
Accounts receivable	56,635	56,635					58,714
Inventories	89,236	89,236					97,305
Other current assets	8,773	8,773					14,910
Property and equipment	79,298	79,298					53,128
Identifiable intangible assets	68,694	68,694					70,057
Goodwill	60,620	60,620					64,950
Other assets	3,755	3,755					7,283
Total assets	367,011	367,011					366,347
Accounts payable	23,415	23,415					29,512
Current maturities of long-term debt	18,081	18,081					17,278
Other current liabilities	32,091	32,091					27,595
Long-term debt	52,498	52,498					47,369
Other liabilities	15,198	15,198					17,551
Total liabilities	141,283	141,283					139,305
Purchase price:
Cash consideration, net of cash acquired	167,688						169,002
Contingent consideration	3,898	$ 3,898					3,898
Gain on previously held shares	20,767						20,767
Existing investment in acquired entity	33,483						33,483
Non-cash consideration related to acquired intercompany balances	(108)						(108)
Total consideration, net of cash acquired	$ 225,728						227,042
Measurement Period Adjustment
Measurement period adjustments, Accounts receivable							(2,079)
Measurement period adjustments, Inventories							(8,069)
Measurement period adjustments, Other current assets							(6,137)
Measurement period adjustments, Property and equipment							26,170
Measurement period adjustments, Identifiable intangible assets							(1,363)
Measurement period adjustments, Goodwill							(4,330)
Measurement period adjustments, Other assets							(3,528)
Measurement period adjustments, Total assets							664
Measurement period adjustments, Accounts payable							(6,097)
Measurement period adjustments, Current maturities of long-term debt							803
Measurement period adjustments, Other current liabilities							4,496
Measurement period adjustments, Long-term debt							5,129
Measurement period adjustments, Other liabilities							(2,353)
Measurement period adjustments, Total liabilities							1,978
Measurement period adjustments, Cash consideration, net of cash acquired							(1,314)
Measurement period adjustments, Total consideration, net of cash acquired							$ (1,314)