Consolidated Statements of Operations and Comprehensive Income (Parenthetical) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Income Statement [Abstract]        
Prior service cost, tax $ 25 $ 26 $ 50 $ 53
Actuarial (gain) loss, tax 832 $ (5) 1,664 $ (10)
Unrealized loss on cash flow hedge, tax $ 11   $ 21