CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income (loss)	$ 150,281	$ 66,547	$ (8,176)
Reconciliation of net income (loss) to net cash provided by operating activities
Depreciation and amortization	30,153	23,271	21,241
Debt discount and deferred loan cost amortization	275	1,752	1,777
Stock-based compensation	4,704		361
Provision for (recovery of) bad debts		(100)	(357)
Inventory obsolescence	1,451	1,259	1,851
Loss on disposal of assets	886	534	950
Deferred income taxes	15,201	220	132
Loss (gain) on debt extinguishment	4,305		(2,251)
Changes in operating assets and liabilities:
Accounts receivable	(8,105)	(50,094)	509
Inventories	(38,227)	(28,279)	4,126
Prepaid expenses and other assets	(6,509)	(4,012)	1,080
Accounts payable	7,651	19,505	5,014
Accrued expenses and other liabilities	5,114	4,104	(2,282)
Net cash provided by operating activities	167,180	34,707	23,975
Cash flows from investing activities
Capital expenditures and other	(70,053)	(32,082)	(21,721)
Proceeds from sale of assets	1,899	1,404	4,363
Net cash used in investing activities	(68,154)	(30,678)	(17,358)
Cash flows from financing activities
Principal payments on long-term debt	(248,529)	(2,569)	(7,908)
Payment of deferred financing costs	(840)
Payments on capital leases	(6,274)	(2,744)	(208)
Net proceeds from IPO and Follow-on Offering	828,168
Distributions to members	(31,848)		(2,055)
Redemption of CW Units	(575,681)
Net cash used in financing activities	(35,004)	(5,313)	(10,171)
Effect of exchange rate changes on cash and cash equivalents	(755)	170	(284)
Net increase (decrease) in cash and cash equivalents	63,267	(1,114)	(3,838)
Cash and cash equivalents
Beginning of period	7,574	8,688	12,526
End of period	$ 70,841	$ 7,574	$ 8,688