Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net unrealized gains (losses) on securities arising during the period, taxes	$ 1,094	$ 1,049	$ (2,249)	$ 7,081
Less: reclassification adjustment for net realized gains included in net income, taxes	0	0	1,132	488
Less: reclassification adjustment to net income, tax benefits	(37)	(37)	(112)	(112)
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, tax benefits	(1,900)	(3,697)	(5,438)	(11,173)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, taxes	$ 1,619	$ 3,284	$ 4,858	$ 9,852