Investments (Details 2) - USD ($) $ in Millions |
Jun. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Available-for-sale securities, by type | ||
| Available-for-sale Securities Fair Value | $ 8,042 | $ 6,413 |
| Available-for-sale Securities, Amortized Cost Basis | 7,344 | 5,952 |
| Available-for-sale Securities Gross Unrealized Gains | 751 | 514 |
| Available-for-sale Securities Gross Unrealized Losses | (53) | (53) |
| Equity Securities | ||
| Available-for-sale securities, by type | ||
| Available-for-sale Securities Fair Value | 1,871 | 1,655 |
| Available-for-sale Securities, Amortized Cost Basis | 1,268 | 1,252 |
| Available-for-sale Securities Gross Unrealized Gains | 634 | 425 |
| Available-for-sale Securities Gross Unrealized Losses | (31) | (22) |
| Debt Securities | ||
| Available-for-sale securities, by type | ||
| Available-for-sale Securities Fair Value | 6,171 | 4,758 |
| Available-for-sale Securities, Amortized Cost Basis | 6,076 | 4,700 |
| Available-for-sale Securities Gross Unrealized Gains | 117 | 89 |
| Available-for-sale Securities Gross Unrealized Losses | $ (22) | $ (31) |
| X | ||||||||||
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|