Retirement and Postretirement Plans - Net Funded Status of Plans (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member]
Amounts recorded in the balance sheet:
Current liabilities	$ (4,169)	$ (4,175)
Noncurrent liabilities	(163,237)	(180,062)
Funded Status	(167,406)	(184,237)
Other Pension Plan, Postretirement or Supplemental Plans [Member]
Amounts recorded in the balance sheet:
Current liabilities	(2,089)	(2,148)
Noncurrent liabilities	(19,750)	(24,236)
Funded Status	$ (21,839)	$ (26,384)