Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net unrealized gains (losses) on securities arising during the period, taxes	$ (1,664)	$ 547
Less: reclassification adjustment for net realized gains included in net income, taxes	1,132	0
Less: reclassification adjustment to net income, tax benefits	(37)	(37)
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, tax benefits	(1,796)	(3,846)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, taxes	$ 1,598	$ 3,384