Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net unrealized gains (losses) on securities arising during the period, taxes	$ (2,543)	$ 1,094	$ (2,382)	$ (2,249)
Less: reclassification adjustment for net realized gains included in net income, net of taxes	0	0	0	1,132
Less: reclassification adjustment to net income, net of tax benefits	37	37	112	112
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	3,583	1,900	10,760	5,438
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, taxes	$ 3,243	$ 1,619	$ 9,729	$ 4,858