Debt (Trust Preferred Securities) (Details)
$ in Millions |
6 Months Ended |
12 Months Ended |
|
|
Jun. 30, 2016
USD ($)
subsidiary
|
Dec. 31, 2015
USD ($)
subsidiary
|
Dec. 31, 2014
USD ($)
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Number of subsidiaries | subsidiary |
9
|
9
|
|
| Maximum period for interest payment deferment (in quarters) |
60 months
|
|
|
| Trust preferred securities, accrued interest |
$ 31
|
$ 27
|
|
| Trust Preferred Securities |
|
247
|
$ 247
|
| Total long-term debt |
$ 247
|
$ 247
|
331
|
| Junior Subordinated Debt [Member] |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Current Period for Interest Payment Deferment (in Quarters) |
54 months
|
|
|
| 3ML plus 3.25% matures 2032 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
3.25%
|
3.25%
|
|
| Trust Preferred Securities |
$ 26
|
$ 26
|
$ 26
|
| Interest rate |
3.89%
|
3.85%
|
3.50%
|
| 3ML plus 3.25% matures 2033 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
3.25%
|
3.25%
|
|
| Trust Preferred Securities |
$ 26
|
$ 26
|
$ 26
|
| Interest rate |
3.88%
|
3.57%
|
3.48%
|
| 3ML plus 3.25% matures 2033 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
3.25%
|
3.25%
|
|
| Trust Preferred Securities |
$ 26
|
$ 26
|
$ 26
|
| Interest rate |
3.88%
|
3.85%
|
3.51%
|
| 3ML plus 2.00% matures 2035 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
2.00%
|
2.00%
|
|
| Trust Preferred Securities |
$ 26
|
$ 26
|
$ 26
|
| Interest rate |
2.63%
|
2.32%
|
2.23%
|
| 3ML plus 2.00% matures 2035 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
2.00%
|
2.00%
|
|
| Trust Preferred Securities |
$ 26
|
$ 26
|
$ 26
|
| Interest rate |
2.63%
|
2.32%
|
2.23%
|
| 3ML plus 1.75% matures 2035 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
1.75%
|
1.75%
|
|
| Trust Preferred Securities |
$ 51
|
$ 51
|
$ 51
|
| Interest rate |
2.40%
|
2.26%
|
1.99%
|
| 3ML plus 1.50% matures 2035 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
1.50%
|
1.50%
|
|
| Trust Preferred Securities |
$ 25
|
$ 25
|
$ 25
|
| Interest rate |
2.13%
|
1.82%
|
1.73%
|
| 3ML plus 1.45% matures 2037 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
1.45%
|
1.45%
|
|
| Trust Preferred Securities |
$ 25
|
$ 25
|
$ 25
|
| Interest rate |
2.10%
|
1.96%
|
1.69%
|
| 3ML plus 2.50% matures 2037 |
|
|
|
| Trust Preferred Securities [Abstract] |
|
|
|
| Basis spread on variable rate (percent) |
2.50%
|
2.50%
|
|
| Trust Preferred Securities |
$ 16
|
$ 16
|
$ 16
|
| Interest rate |
3.15%
|
3.01%
|
2.74%
|