Condensed Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net unrealized gains (losses) on securities arising during the period, taxes (benefits)	$ 148	$ 4,905
Effective portion of foreign currency hedge net unrealized gain, taxes	0	638
Less: reclassification adjustment to net income, net of (taxes) benefits	(289)	(35)
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	2,502	2,257
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, taxes	$ 2,301	$ 2,052