Condensed Consolidated Statements of Comprehensive Income/(Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ 29,315	$ 40,265	$ 47,883	$ (4,948)
Other comprehensive income/(loss), net of taxes:
Interest rate swaps (net of $(0.2) million, $0.1 million, $(0.3) million and $0.4 million tax (expense)/benefit, respectively)	274	(135)	398	(623)
Qualified pension and post-employment benefit plans (net of $18.5 million, $0 million, $37.7 million and $0 million tax benefit, respectively)	(37,515)	(55,691)	(74,015)	615,334
Total other comprehensive income/(loss)	(37,241)	(55,826)	(73,617)	614,711
Comprehensive income/(loss)	$ (7,926)	$ (15,561)	$ (25,734)	$ 609,763