Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Change in unrealized loss on derivative instruments, tax expense	$ (6)	$ (158)	$ (161)
Pension plan adjustments, tax benefit	$ 2,412	$ 7,382	$ 23,583