Statements of Consolidated Comprehensive Income Other Comprehensive Income, Deferred Tax - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Comprehensive Income, Deferred Tax [Abstract]
Amortization of net actuarial loss included in net periodic benefit expense or income, tax	$ 1,290	$ 756	$ 2,575	$ 1,550
Amortization of prior service credit included in net periodic benefit expense or income, tax	$ 79	$ 120	$ 159	$ 242