Fair Value Measurements and Other Investments - Summary of Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 4,485	$ 4,771
China Southern Airlines [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ownership interest	2.20%
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 4,485	4,771
Restricted cash and short-term investments	154	318
Long-term investments	189
Total	4,828	5,089
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	16	188
Restricted cash and short-term investments	12	108
Long-term investments	189
Total	217	296
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	4,469	4,583
Restricted cash and short-term investments	142	210
Long-term investments	0
Total	4,611	4,793
Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Restricted cash and short-term investments	0	0
Long-term investments	0
Total	0	0
Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	16	188
Recurring [Member] | Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	16	188
Recurring [Member] | Money Market Funds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Money Market Funds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,658	1,620
Recurring [Member] | Corporate debt [Member] | Maturity Dates Exceeding One Year [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	101	341
Recurring [Member] | Corporate debt [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Corporate debt [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,658	1,620
Recurring [Member] | Corporate debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	2,436	2,663
Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Maturity Dates Exceeding One Year [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	877	700
Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	2,436	2,663
Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	375	300
Recurring [Member] | Repurchase Agreements [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Recurring [Member] | Repurchase Agreements [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	375	300
Recurring [Member] | Repurchase Agreements [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 4,482	4,768
American Airlines, Inc. [Member] | China Southern Airlines [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ownership interest	2.20%
American Airlines, Inc. [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 4,482	4,768
Restricted cash and short-term investments	154	318
Long-term investments	189
Total	4,825	5,086
American Airlines, Inc. [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	14	186
Restricted cash and short-term investments	12	108
Long-term investments	189
Total	215	294
American Airlines, Inc. [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	4,468	4,582
Restricted cash and short-term investments	142	210
Long-term investments	0
Total	4,610	4,792
American Airlines, Inc. [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Restricted cash and short-term investments	0	0
Long-term investments	0
Total	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	14	186
American Airlines, Inc. [Member] | Recurring [Member] | Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	14	186
American Airlines, Inc. [Member] | Recurring [Member] | Money Market Funds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Money Market Funds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,658	1,620
American Airlines, Inc. [Member] | Recurring [Member] | Corporate debt [Member] | Maturity Dates Exceeding One Year [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	101	341
American Airlines, Inc. [Member] | Recurring [Member] | Corporate debt [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Corporate debt [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,658	1,620
American Airlines, Inc. [Member] | Recurring [Member] | Corporate debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	2,435	2,662
American Airlines, Inc. [Member] | Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Maturity Dates Exceeding One Year [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	877	700
American Airlines, Inc. [Member] | Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	2,435	2,662
American Airlines, Inc. [Member] | Recurring [Member] | Bank Notes / Certificates of Deposit / Time Deposits [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	375	300
American Airlines, Inc. [Member] | Recurring [Member] | Repurchase Agreements [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
American Airlines, Inc. [Member] | Recurring [Member] | Repurchase Agreements [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	375	300
American Airlines, Inc. [Member] | Recurring [Member] | Repurchase Agreements [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 0	$ 0