Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		3 Months Ended					9 Months Ended			12 Months Ended
		Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016		Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016		Dec. 31, 2016		Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)		$ 132,895	$ 7,407	$ 4,455	[1]	$ (1,358)	$ 118,561	$ 5,215	[1]	$ 7,299		$ (6,788)
Adjustments to reconcile net income to net cash provided by (used by) operating activities:
Depreciation and amortization		13,075		11,737	[1]		38,432	38,411	[1]
Depreciation and amortization of discontinued operations							7,723	8,766
Amortization of debt issuance costs							3,237	3,048
Write-off of debt issuance costs							8,054	2,589
Gain on disposal of discontinued operations, net of tax and cost to sell							(129,353)
Compensation expense from issuance of share-based awards							3,220	3,051
Other							439	421
Changes in operating assets and liabilities:
Accounts receivable							(15,094)	(24,422)
Inventories							(10,764)	1,663
Accounts payable							(3,317)	629
Income taxes payable							(19,178)	(2,153)
Other							(1,674)	9,073
Net cash provided by operating activities							286	46,291
Cash flows from investing activities:
Acquisition of property, plant and equipment							(31,674)	(32,166)
Proceeds from measurement period adjustments to previous acquisition								1,635
Proceeds from disposals of property, plant and equipment							639	366
Short term investment							(8,000)
Proceeds from sale of business, net of cash sold							371,436
Net cash provided by (used by) investing activities							332,401	(30,165)
Cash flows from financing activities:
Debt issue costs paid							(6,545)	(3,692)
Dividends paid							(5,764)	(5,677)
Proceeds from long-term debt							317,000	39,000
Repayment of long-term debt							(301,313)	(39,562)
Proceeds from (repayment of) short-term debt, net							(3,968)	(4,101)
Proceeds from issuance of stock and exercise of stock options							2,945	2,553
Shares withheld to satisfy income tax withholding							(580)	(159)
Principal payments on capital leases							(2,855)	(3,465)
Net cash used by financing activities							(1,080)	(15,103)
Effect of exchange rate changes on cash flows							1,368	(1,322)
Net change in cash and cash equivalents							332,975	(299)
Cash and cash equivalents at beginning of period	[2]		$ 14,405			$ 15,087	14,405	15,087		15,087
Cash and cash equivalents at end of period		$ 347,380		$ 14,788			$ 347,380	$ 14,788		$ 14,405	[2]	$ 15,087	[2]

[1] Includes the effects of discontinued operations (Note 2) and prior periods' revisions (Note 1 and Note 15)

[2] Beginning balance for the nine-month period ended September 30, 2017, includes $8.1 million of cash that was included in current assets of discontinued operations.