Consolidated Statements of Changes in Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Stockholders Equity [Abstract]
Amortization of terminated hedge, income tax effect	$ 120	$ 120	$ 120
Unrealized derivative gains and losses on cash flow hedges, income tax effect	2,283	6,529	6,390
Minimum pension liability, income tax effect	$ (817)	$ 5,356	$ 5,670