Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Changes in operating assets and liabilities
Accounts receivable, net	$ (1,010)	$ 13,029
Inventories	(1,862)	2,699
Other current assets and other assets	(1,100)	(119)
Income taxes	(1,339)	11,690
Accounts payable	(3,208)	3,205
Accrued expenses and other current liabilities	(2,778)	(14,300)
Accrued compensation related costs	(17,901)	(22,298)
Other liabilities	(1,871)	(2,538)
Operating lease liabilities	(19,179)
Changes in operating assets and liabilities on cash flows from operating activities	(50,248)	(8,632)
Non-cash financing and investing activities:
Additional consideration and issuance of seller notes in connection with acquistions	5,345
Purchase of property, plant and equipment in accounts payable at period end	3,437	960
Purchase of property, plant and equipment through vendor financing	$ 2,200
Additions to property, plant and equipment acquired through financing obligations		1,354
Retirements of financed property, plant and equipment and related obligations		$ 2,246