Other Comprehensive Income Details 2 (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ 4,256	$ 1,917	$ 822	$ 2,261
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	360	305	140	437
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	3,896	1,612	682	1,824
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, Portion Attributable to Parent	4,687	5,054	9,498	10,093
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Parent	1,123	1,301	2,248	2,628
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	3,564	3,753	7,250	7,465
Interest Rate Swap [Member]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	158	505	435	849
Cross Currency Swap [Member]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	4,098	$ 1,412	387	$ 1,412
Foreign Currency Transaction Gain (Loss), Unrealized	4,800		1,800
Interest Income, Other	$ 700		$ 1,400