CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 24,691	$ 32,836
Derivative instruments:
Net unrealized gain (loss), net of tax benefit (expense) of $(599) and $(38)	(422)	58
Reclassification of net realized loss, net of tax benefit of $1,323 and $3,300	3,116	5,053
Pension and other postretirement benefits activity, net of tax expense of $718 and $631	457	966
Total other comprehensive income	3,151	6,077
COMPREHENSIVE INCOME	27,842	38,913
Less: Comprehensive income attributable to noncontrolling interests	8,925	8,392
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 18,917	$ 30,521