CONSOLIDATED STATEMENTS OF CASH FLOW (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
OPERATING ACTIVITIES
Net income	$ 1,233	$ 10,101	$ 12,207	$ 23,417
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,201	15,142	29,845	28,266
Amortization	2,632	2,817	5,281	4,513
Change in other noncurrent liabilities	(758)	(3,371)	(2,354)	(4,735)
Change in deferred taxes and other liabilities	(6,745)	(1,457)	(7,357)	1,072
Provision for write-off of property, plant and equipment	534	484	830	1,076
Non-cash interest expense	212		423
Compensation and benefits paid or payable in Class A Common Stock	681	668	1,670	1,532
Changes in operating assets and liabilities that provided/(used) cash, net of impact of business acquisition:
Accounts receivable	(14,395)	(10,384)	(15,136)	(11,286)
Inventories	1,655	(6,027)	(13,266)	(7,375)
Prepaid expenses and other current assets	(651)	2,561	(2,568)	(2,821)
Income taxes prepaid and receivable	(2,817)	3,732	(2,817)	1,837
Accounts payable	(1,459)	1,267	2,065	2,899
Accrued liabilities	10,071	689	(900)	(8,154)
Income taxes payable	1,978	2,903	(508)	(933)
Contract receivables	(3,621)	(7,768)	(7,536)	(7,768)
Other, net	4,638	7,291	3,938	2,490
Net cash provided by operating activities	8,389	18,648	3,817	24,030
INVESTING ACTIVITIES
Purchase of business, net of cash acquired		(187,000)		(187,000)
Purchases of property, plant and equipment	(21,360)	(20,112)	(46,405)	(28,105)
Purchased software	(353)	(589)	(391)	(671)
Proceeds from sale or involuntary conversion of assets		1,736		1,736
Net cash used in investing activities	(21,713)	(205,965)	(46,796)	(214,040)
FINANCING ACTIVITIES
Proceeds from borrowings	16,114	207,134	32,259	219,530
Principal payments on debt	(540)	(426)	(21,142)	(22,824)
Debt acquisition costs		(1,571)		(1,771)
Swap termination payment		(5,175)		(5,175)
Taxes paid in lieu of share issuance			(1,364)	(1,272)
Proceeds from options exercised	100	185	175	390
Dividends paid	(5,467)	(5,454)	(10,926)	(10,897)
Net cash (used in)/provided by financing activities	10,207	194,693	(998)	177,981
Effect of exchange rate changes on cash and cash equivalents	(1,424)	(966)	1,027	2,941
(Decrease)/increase in cash and cash equivalents	(4,541)	6,410	(42,950)	(9,088)
Cash and cash equivalents at beginning of period	143,333	169,615	181,742	185,113
Cash and cash equivalents at end of period	$ 138,792	$ 176,025	$ 138,792	$ 176,025