Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Net income		$ 711	$ 16,270	$ 6,367		$ 36,620
Other comprehensive income, net of tax:
Amortization of prior service credit included in net periodic cost, net of tax of $(848), $(867), $(1,697) and $(1,734)	[1]	(1,328)	(1,356)	(2,656)		(2,712)
Amortization of actuarial loss included in net periodic cost, net of tax of $1,900, $1,568, $3,837 and $3,245	[1]	2,974	2,452	6,003		5,074
Other comprehensive income, net of tax	[1]	1,646	1,096	3,347		2,362
Comprehensive income		$ 2,357	$ 17,366	$ 9,714	[1]	$ 38,982

[1] Amortization of prior service credit (cost) and amortization of actuarial loss are included in the computation of net periodic cost (benefit).