Accumulated Other Comprehensive Income (Loss) - Rollforward of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net loss, including settlement charges, net of tax of $1,168 and $996, respectively	$ 1,890	$ 1,851
Pension and Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2015	263
Other comprehensive income (loss) before reclassifications	(9)
Amortization of net loss, including settlement charges, net of tax of $1,168 and $996, respectively	1,812
Change in accumulated other comprehensive income (loss)	1,803
Balance as of March 31, 2016	$ 2,066