Closed Block (Liabilities and Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Closed Block Liabilities
Future policy benefits	$ 40,976	$ 41,278
Other policy-related balances	240	249
Policyholder dividends payable	491	468
Policyholder dividend obligation	3,343	1,783	$ 3,155
Other liabilities	726	380
Total closed block liabilities	45,776	44,158
Assets Designated to the Closed Block
Fixed maturity securities available-for-sale, at estimated fair value	29,404	27,556
Equity securities available-for-sale, at estimated fair value	110	111
Mortgage loans	5,825	6,022
Policy loans	4,558	4,642
Real estate and real estate joint ventures	566	462
Other invested assets	1,106	1,066
Total investments	41,569	39,859
Cash and cash equivalents	220	236
Accrued investment income	463	474
Premiums, reinsurance and other receivables	51	56
Current income tax recoverable	0	11
Deferred income tax assets	200	234
Total assets designated to the closed block	42,503	40,870
Excess of closed block liabilities over assets designated to the closed block	3,273	3,288
Amounts included in accumulated other comprehensive income (loss) (“AOCI”)
Unrealized investment gains (losses), net of income tax	2,435	1,382
Unrealized gains (losses) on derivatives, net of income tax	100	76
Allocated to policyholder dividend obligation, net of income tax	(2,173)	(1,159)
Total amounts included in AOCI	362	299
Maximum future earnings to be recognized from closed block assets and liabilities	$ 3,635	$ 3,587