Supplemental Condensed Consolidating Financial Information - Cash Flows (Details) - USD ($)
$ in Millions |
3 Months Ended |
Mar. 31, 2018 |
Mar. 31, 2017 |
| Operating activities: |
|
|
| Net cash provided by operating activities |
$ 394
|
$ 719
|
| Investing activities: |
|
|
| Purchases of investments |
(389)
|
(733)
|
| Proceeds from sales and maturities of investments |
543
|
433
|
| Purchases of property, equipment and capitalized software |
(4)
|
(26)
|
| Decrease in restricted investments held-to-maturity |
0
|
(5)
|
| Capital contributions to subsidiaries |
0
|
0
|
| Dividends from subsidiaries |
|
0
|
| Change in amounts due to/from affiliates |
0
|
0
|
| Other, net |
(5)
|
(6)
|
| Net cash provided by (used in) investing activities |
145
|
(337)
|
| Financing activities: |
|
|
| Cash paid for financing transaction fees |
(5)
|
0
|
| Proceeds from employee stock plans |
0
|
1
|
| Other, net |
0
|
(2)
|
| Net cash used in financing activities |
(5)
|
(1)
|
| Net increase in cash, cash equivalents, and restricted cash and cash equivalents |
534
|
381
|
| Cash, cash equivalents, and restricted cash and cash equivalents at beginning of period |
3,290
|
2,912
|
| Cash, cash equivalents, and restricted cash and cash equivalents at end of period |
3,824
|
3,293
|
| Eliminations |
|
|
| Operating activities: |
|
|
| Net cash provided by operating activities |
0
|
0
|
| Investing activities: |
|
|
| Purchases of investments |
0
|
0
|
| Proceeds from sales and maturities of investments |
0
|
0
|
| Purchases of property, equipment and capitalized software |
0
|
0
|
| Decrease in restricted investments held-to-maturity |
|
0
|
| Capital contributions to subsidiaries |
0
|
0
|
| Dividends from subsidiaries |
|
0
|
| Change in amounts due to/from affiliates |
0
|
0
|
| Other, net |
0
|
0
|
| Net cash provided by (used in) investing activities |
0
|
0
|
| Financing activities: |
|
|
| Cash paid for financing transaction fees |
0
|
|
| Proceeds from employee stock plans |
|
0
|
| Other, net |
|
0
|
| Net cash used in financing activities |
0
|
0
|
| Net increase in cash, cash equivalents, and restricted cash and cash equivalents |
0
|
0
|
| Cash, cash equivalents, and restricted cash and cash equivalents at beginning of period |
0
|
0
|
| Cash, cash equivalents, and restricted cash and cash equivalents at end of period |
0
|
0
|
| Parent Guarantor | Reportable Legal Entities |
|
|
| Operating activities: |
|
|
| Net cash provided by operating activities |
6
|
144
|
| Investing activities: |
|
|
| Purchases of investments |
(130)
|
0
|
| Proceeds from sales and maturities of investments |
5
|
92
|
| Purchases of property, equipment and capitalized software |
(1)
|
(18)
|
| Decrease in restricted investments held-to-maturity |
|
0
|
| Capital contributions to subsidiaries |
(80)
|
(106)
|
| Dividends from subsidiaries |
|
50
|
| Change in amounts due to/from affiliates |
(3)
|
(60)
|
| Other, net |
2
|
0
|
| Net cash provided by (used in) investing activities |
(207)
|
(42)
|
| Financing activities: |
|
|
| Cash paid for financing transaction fees |
(5)
|
|
| Proceeds from employee stock plans |
|
1
|
| Other, net |
|
(2)
|
| Net cash used in financing activities |
(5)
|
(1)
|
| Net increase in cash, cash equivalents, and restricted cash and cash equivalents |
(206)
|
101
|
| Cash, cash equivalents, and restricted cash and cash equivalents at beginning of period |
513
|
86
|
| Cash, cash equivalents, and restricted cash and cash equivalents at end of period |
307
|
187
|
| Other Guarantors | Reportable Legal Entities |
|
|
| Operating activities: |
|
|
| Net cash provided by operating activities |
9
|
21
|
| Investing activities: |
|
|
| Purchases of investments |
0
|
0
|
| Proceeds from sales and maturities of investments |
0
|
0
|
| Purchases of property, equipment and capitalized software |
(2)
|
(5)
|
| Decrease in restricted investments held-to-maturity |
|
0
|
| Capital contributions to subsidiaries |
0
|
1
|
| Dividends from subsidiaries |
|
0
|
| Change in amounts due to/from affiliates |
(2)
|
2
|
| Other, net |
(6)
|
(6)
|
| Net cash provided by (used in) investing activities |
(10)
|
(8)
|
| Financing activities: |
|
|
| Cash paid for financing transaction fees |
0
|
|
| Proceeds from employee stock plans |
|
0
|
| Other, net |
|
0
|
| Net cash used in financing activities |
0
|
0
|
| Net increase in cash, cash equivalents, and restricted cash and cash equivalents |
(1)
|
13
|
| Cash, cash equivalents, and restricted cash and cash equivalents at beginning of period |
28
|
6
|
| Cash, cash equivalents, and restricted cash and cash equivalents at end of period |
27
|
19
|
| Non-Guarantors | Reportable Legal Entities |
|
|
| Operating activities: |
|
|
| Net cash provided by operating activities |
379
|
554
|
| Investing activities: |
|
|
| Purchases of investments |
(259)
|
(733)
|
| Proceeds from sales and maturities of investments |
538
|
341
|
| Purchases of property, equipment and capitalized software |
(1)
|
(3)
|
| Decrease in restricted investments held-to-maturity |
|
(5)
|
| Capital contributions to subsidiaries |
80
|
105
|
| Dividends from subsidiaries |
|
(50)
|
| Change in amounts due to/from affiliates |
5
|
58
|
| Other, net |
(1)
|
0
|
| Net cash provided by (used in) investing activities |
362
|
(287)
|
| Financing activities: |
|
|
| Cash paid for financing transaction fees |
0
|
|
| Proceeds from employee stock plans |
|
0
|
| Other, net |
|
0
|
| Net cash used in financing activities |
0
|
0
|
| Net increase in cash, cash equivalents, and restricted cash and cash equivalents |
741
|
267
|
| Cash, cash equivalents, and restricted cash and cash equivalents at beginning of period |
2,749
|
2,820
|
| Cash, cash equivalents, and restricted cash and cash equivalents at end of period |
$ 3,490
|
$ 3,087
|