Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net change related to employee benefit plans, tax expense	$ 1,037	$ 85	$ 2,046	$ 209
Net change in derivative instruments, tax (benefit) expense	(898)	(2,049)	(1,386)	(5,352)
Net change in available-for-sale investments, tax (benefit) expense	$ (75)	$ 21	$ 110	$ 21