CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating revenues
Electric	$ 2,299,060	$ 2,185,119
Natural gas	625,703	565,689
Other	21,659	21,465
Total operating revenues	2,946,422	2,772,273
Operating expenses
Electric fuel and purchased power	925,221	861,852
Cost of natural gas sold and transported	365,134	312,117
Cost of sales — other	8,587	8,245
Operating and maintenance expenses	586,430	577,410
Conservation and demand side management program expenses	67,533	57,436
Depreciation and amortization	365,204	320,020
Taxes (other than income taxes)	142,094	145,323
Total operating expenses	2,460,203	2,282,403
Operating income	486,219	489,870
Other income, net	6,446	4,250
Equity earnings of unconsolidated subsidiaries	7,875	13,182
Allowance for funds used during construction — equity	14,313	13,113
Interest charges and financing costs
Interest charges — includes other financing costs of $5,858 and $6,336, respectively	165,934	156,443
Allowance for funds used during construction — debt	(7,022)	(5,990)
Total interest charges and financing costs	158,912	150,453
Income before income taxes	355,941	369,962
Income taxes	116,664	128,650
Net income	$ 239,277	$ 241,312
Weighted average common shares outstanding:
Basic (in shares)	508,278	508,667
Diluted (in shares)	508,774	509,150
Earnings per average common share:
Basic (in dollars per share)	$ 0.47	$ 0.47
Diluted (in dollars per share)	0.47	0.47
Cash dividends declared per common share (in dollars per share)	$ 0.36	$ 0.34