CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]        
Net income $ 12,933 $ 29,834 [1] $ 29,463 $ 23,827 [1]
Other comprehensive income (loss), net of tax        
Translation adjustments 442 209 3,133 (4,421)
Minimum pension liability adjustments 7,418 932 8,333 1,864
Cash flow hedge adjustments 100 48 (427) (428)
Total other comprehensive income (loss), net of tax 7,960 1,189 11,039 (2,985)
Comprehensive income $ 20,893 $ 31,023 $ 40,502 $ 20,842
[1] During the third quarter of 2015, the Company elected a change in accounting principle for the valuation method of certain inventories to the last-in, first-out (“LIFO”) method from the first-in, first out method (“FIFO”). This change required retrospective application. As such, the financial statements presented for prior periods are titled “Revised”.