Correction of Errors in Previously Reported Consolidated Financial Statements (BalSh) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Cash and cash equivalents	$ 3,052	$ 2,339	$ 2,635	$ 3,243
Accounts receivable, net
Trade	833	1,343
Other	65	57
Materials and supplies, net	561	627
Restricted cash	466	340
Other current assets	121	92
Total current assets	5,098	4,798
Property and equipment	27,372	26,265
Less accumulated depreciation	(6,279)	(5,456)
Property and equipment, net	21,093	20,809
Deferred income taxes, net	298	411
Other assets	400	413
Total assets	26,889	26,431
Liabilities and equity
Accounts payable	206	455
Accrued income taxes	95	55
Debt due within one year	724	1,093
Other current liabilities	960	1,062
Total current liabilities	1,985	2,665
Long-term debt	7,740	7,397
Deferred income taxes, net	178	229
Other long-term liabilities	1,153	1,135
Total long-term liabilities	9,071	8,761
Commitments and contingencies
Redeemable noncontrolling interest	28	5	11
Shares	36	5,193
Additional paid-in capital	10,993	5,736
Treasury shares, at cost		(240)
Retained earnings	5,056	4,278
Accumulated other comprehensive loss	(283)	(277)
Total controlling interest shareholders' equity	15,802	14,690
Noncontrolling interest	3	310
Total equity	15,805	15,000	$ 14,104	$ 16,719
Total liabilities and equity	$ 26,889	26,431
Previously reported
Assets
Cash and cash equivalents		2,339
Accounts receivable, net
Trade		1,343
Other		36
Materials and supplies, net		635
Restricted cash		340
Other current assets		92
Total current assets		4,785
Property and equipment		26,274
Less accumulated depreciation		(5,456)
Property and equipment, net		20,818
Deferred income taxes, net		316
Other assets		410
Total assets		26,329
Liabilities and equity
Accounts payable		448
Accrued income taxes		82
Debt due within one year		1,093
Other current liabilities		1,046
Total current liabilities		2,669
Long-term debt		7,397
Deferred income taxes, net		339
Other long-term liabilities		1,108
Total long-term liabilities		8,844
Commitments and contingencies
Redeemable noncontrolling interest		8
Shares		5,193
Additional paid-in capital		5,739
Treasury shares, at cost		(240)
Retained earnings		4,140
Accumulated other comprehensive loss		(334)
Total controlling interest shareholders' equity		14,498
Noncontrolling interest		310
Total equity		14,808
Total liabilities and equity		26,329
Adjusted
Accounts receivable, net
Other		21
Materials and supplies, net		(8)
Total current assets		13
Property and equipment		(9)
Property and equipment, net		(9)
Deferred income taxes, net		95
Other assets		3
Total assets		102
Liabilities and equity
Accounts payable		7
Accrued income taxes		(27)
Other current liabilities		16
Total current liabilities		(4)
Deferred income taxes, net		(110)
Other long-term liabilities		27
Total long-term liabilities		(83)
Commitments and contingencies
Redeemable noncontrolling interest		(3)
Additional paid-in capital		(3)
Retained earnings		138
Accumulated other comprehensive loss		57
Total controlling interest shareholders' equity		192
Total equity		192
Total liabilities and equity		$ 102