Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Tax provision on defined benefit pension plans	$ 21	$ 12	$ 63	$ 37
Tax provision on loss on derivative instrument classified as a cash flow hedge	$ 604	$ 2,139	$ 484	$ 2,148