Revenue Recognition (Schedule of Consolidated Statement of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES
Net income	$ 28,484	$ 15,220	$ 69,272	$ 27,427
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	17,436	15,522	52,852	45,367
Amortization	2,366	2,608	7,571	7,889
Change in other noncurrent liabilities	(5,102)	(168)	(6,333)	(2,522)
Change in deferred taxes and other liabilities	1,331	(3,263)	(5,571)	(10,620)
Provision for write-off of property, plant and equipment	2,131	1,086	3,255	1,916
Non-cash interest expense	150	211	304	634
Compensation and benefits paid or payable in Class A Common Stock	543	195	1,879	1,865
Fair value adjustment on foreign currency option	(10)	2	61	131
Write-off of intangible assets in a discontinued product line		4,149		4,149
Changes in operating assets and liabilities that provided/(used) cash:
Accounts receivable	(4,177)	(4,645)	(48,547)	(19,781)
Contract assets	3,040		(8,721)
Inventories	(2,228)	(3,944)	(12,843)	(17,210)
Prepaid expenses and other current assets	103	(601)	(5,117)	(3,298)
Income taxes prepaid and receivable	(551)		(454)	(2,817)
Accounts payable	(2,728)	(4,769)	6,154	(2,704)
Accrued liabilities	7,565	5,425	12,233	4,525
Income taxes payable	6,766	3,472	13,355	2,964
Noncurrent receivables	(4,676)	(8,107)	(8,846)	(15,643)
Other, net	(5,728)	(4,495)	(9,049)	(557)
Net cash provided by operating activities	44,715	17,898	61,455	21,715
Net cash used in investing activities	(21,519)	(15,466)	(60,694)	(62,262)
Net cash (used in)/provided by financing activities	(12,904)	4,393	(16,474)	3,395
Effect of exchange rate changes on cash and cash equivalents	(4,443)	7,848	(7,421)	8,875
(Decrease)/increase in cash and cash equivalents	5,849	14,673	(23,134)	(28,277)
Cash and cash equivalents at beginning of period	154,744	138,792	183,727	181,742
Cash and cash equivalents at end of period	160,593	$ 153,465	160,593	$ 153,465
As reported [Member]
OPERATING ACTIVITIES
Net income	28,484		69,272
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	17,436		52,852
Amortization	2,366		7,571
Change in other noncurrent liabilities	(5,102)		(6,333)
Change in deferred taxes and other liabilities	1,331		(5,571)
Provision for write-off of property, plant and equipment	2,131		3,255
Non-cash interest expense	150		304
Compensation and benefits paid or payable in Class A Common Stock	543		1,879
Fair value adjustment on foreign currency option	(10)		61
Write-off of intangible assets in a discontinued product line
Changes in operating assets and liabilities that provided/(used) cash:
Accounts receivable	(4,177)		(48,547)
Contract assets	3,040		(8,721)
Inventories	(2,228)		(12,843)
Prepaid expenses and other current assets	103		(5,117)
Income taxes prepaid and receivable	(551)		(454)
Accounts payable	(2,728)		6,154
Accrued liabilities	7,565		12,233
Income taxes payable	6,766		13,355
Noncurrent receivables	(4,676)		(8,846)
Other, net	(5,728)		(9,049)
Net cash provided by operating activities	44,715		61,455
Net cash used in investing activities	(21,519)		(60,694)
Net cash (used in)/provided by financing activities	(12,904)		(16,474)
Effect of exchange rate changes on cash and cash equivalents	(4,443)		(7,421)
(Decrease)/increase in cash and cash equivalents	5,849		(23,134)
Cash and cash equivalents at beginning of period	154,744		183,727
Cash and cash equivalents at end of period	160,593		160,593
Adjustments to reverse effects of ASC 606 [Member]
OPERATING ACTIVITIES
Net income	(767)		(3,416)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation
Amortization
Change in other noncurrent liabilities
Change in deferred taxes and other liabilities	(431)		(1,539)
Provision for write-off of property, plant and equipment
Non-cash interest expense
Compensation and benefits paid or payable in Class A Common Stock
Fair value adjustment on foreign currency option
Write-off of intangible assets in a discontinued product line
Changes in operating assets and liabilities that provided/(used) cash:
Accounts receivable	1,348		(2,379)
Contract assets	(3,040)		8,721
Inventories	2,902		(1,320)
Prepaid expenses and other current assets
Income taxes prepaid and receivable
Accounts payable
Accrued liabilities	(12)		(67)
Income taxes payable
Noncurrent receivables
Other, net
Net cash provided by operating activities
Net cash used in investing activities
Net cash (used in)/provided by financing activities
Effect of exchange rate changes on cash and cash equivalents
(Decrease)/increase in cash and cash equivalents
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
As adjusted to exclude adoption of ASC 606 [Member]
OPERATING ACTIVITIES
Net income	27,717		65,856
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	17,436		52,852
Amortization	2,366		7,571
Change in other noncurrent liabilities	(5,102)		(6,333)
Change in deferred taxes and other liabilities	900		(7,110)
Provision for write-off of property, plant and equipment	2,131		3,255
Non-cash interest expense	150		304
Compensation and benefits paid or payable in Class A Common Stock	543		1,879
Fair value adjustment on foreign currency option	(10)		61
Write-off of intangible assets in a discontinued product line
Changes in operating assets and liabilities that provided/(used) cash:
Accounts receivable	(2,829)		(50,926)
Contract assets
Inventories	674		(14,163)
Prepaid expenses and other current assets	103		(5,117)
Income taxes prepaid and receivable	(551)		(454)
Accounts payable	(2,728)		6,154
Accrued liabilities	7,553		12,166
Income taxes payable	6,766		13,355
Noncurrent receivables	(4,676)		(8,846)
Other, net	(5,728)		(9,049)
Net cash provided by operating activities	44,715		61,455
Net cash used in investing activities	(21,519)		(60,694)
Net cash (used in)/provided by financing activities	(12,904)		(16,474)
Effect of exchange rate changes on cash and cash equivalents	(4,443)		(7,421)
(Decrease)/increase in cash and cash equivalents	5,849		(23,134)
Cash and cash equivalents at beginning of period	154,744		183,727
Cash and cash equivalents at end of period	$ 160,593		$ 160,593