Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Current assets
Cash and cash equivalents	$ 15	$ 19	$ 25
Receivables
Energy marketing	429	445	430
Natural gas, unbilled revenues and other	355	516	445
Less allowance for uncollectible accounts	38	29	46
Total receivables, net	746	932	829
Inventories
Natural gas	398	622	395
Other	29	29	26
Total inventories	427	651	421
Derivative instruments, including cash collateral	100	206	158
Current deferred income taxes	63	0	26
Prepaid expenses	60	218	51
Regulatory assets	47	68	48
Other	16	21	14
Total current assets	1,474	2,115	1,572
Long-term assets and other deferred debits
Property, plant and equipment	13,039	12,566	11,903
Less accumulated depreciation	2,891	2,775	2,524
Property, plant and equipment, net	10,148	9,791	9,379
Goodwill	1,813	1,813	1,827
Regulatory assets	679	670	642
Intangible assets	101	109	112
Other	273	256	303
Total long-term assets and other deferred debits	13,014	12,639	12,263
Total assets	14,488	14,754	13,835
Current liabilities
Short-term debt	114	1,010	459
Current portion of long-term debt	575	545	125
Energy marketing trade payables	436	418	455
Other accounts payable – trade	278	255	272
Accrued expenses	221	200	183
Regulatory liabilities	156	134	154
Customer deposits and credit balances	143	165	115
Derivative instruments, including cash collateral	65	44	43
Accrued environmental remediation liabilities	59	67	83
Temporary LIFO liquidation	49	0	38
Current deferred income taxes	0	31	0
Other	109	131	120
Total current liabilities	2,205	3,000	2,047
Long-term liabilities and other deferred credits
Long-term debt	3,709	3,275	3,452
Accumulated deferred income taxes	1,992	1,912	1,780
Regulatory liabilities	1,627	1,611	1,622
Accrued pension and retiree welfare benefits	513	515	526
Accrued environmental remediation liabilities	379	364	346
Other	89	102	73
Total long-term liabilities and other deferred credits	8,309	7,779	7,799
Total liabilities and other deferred credits	10,514	10,779	9,846
Commitments, guarantees and contingencies (see Note 11)
Contingently redeemable noncontrolling interest	41	0	0
Equity
Common stock, $5 par value; 750,000,000 shares authorized; outstanding: 120,741,810 shares at June 30, 2016, 120,376,721 shares at December 31, 2015, and 120,081,995 shares at June 30, 2015	605	603	601
Additional paid-in capital	2,133	2,099	2,099
Retained earnings	1,424	1,421	1,425
Accumulated other comprehensive loss	(221)	(186)	(169)
Treasury shares, at cost: 216,523 shares at June 30, 2016, December 31, 2015, and June 30, 2015	(8)	(8)	(8)
Total common shareholders’ equity	3,933	3,929	3,948
Noncontrolling interest	0	46	41
Total equity	3,933	3,975	3,989
Total liabilities, redeemable noncontrolling interest and equity	$ 14,488	$ 14,754	$ 13,835