Condensed Consolidated Statements of Comprehensive Income (Unaudited) Statement - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 41,260	$ 40,420	$ 56,698	$ 67,902
Other comprehensive income/(loss)
Market value adjustments to marketable securities, net of tax	0	(480)	0	(86)
Market value adjustments on interest rate swap, net of tax	50	(439)	1,580	(3,038)
Foreign currency translation adjustments	3,135	(6,285)	16,683	5,309
Supplemental benefit plans adjustments, net of tax	1,731	(107)	1,625	(213)
Total other comprehensive income/(loss)	4,916	(7,311)	19,888	1,972
Comprehensive income	$ 46,176	$ 33,109	$ 76,586	$ 69,874

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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