Investments (Fixed Maturity and Equity Securities Available-For-Sale by Sector) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale Securities [Abstract]
Amortized Cost	$ 332,542	$ 333,599
Cost or Amortized Cost	3,241	3,012
Gross Unrealized OTTI Loss	180	218	361
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	355,069	350,187
Equity securities	3,693	3,402
Fixed maturity securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	332,542	333,599
Gross Unrealized Gain	25,295	21,180
Gross Unrealized Temporary Loss	2,588	4,374
Gross Unrealized OTTI Loss	180	218
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	355,069	350,187
U.S. corporate securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	100,806	100,203
Gross Unrealized Gain	9,133	7,495
Gross Unrealized Temporary Loss	739	1,229
Gross Unrealized OTTI Loss	0	0
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	109,200	106,469
Foreign corporate securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	59,963	59,778
Gross Unrealized Gain	4,543	3,939
Gross Unrealized Temporary Loss	329	565
Gross Unrealized OTTI Loss	0	0
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	64,177	63,152
Foreign government debt securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	50,691	50,717
Gross Unrealized Gain	4,313	4,107
Gross Unrealized Temporary Loss	297	387
Gross Unrealized OTTI Loss	0	0
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	54,707	54,437
RMBS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	36,047	34,167
Gross Unrealized Gain	1,728	1,584
Gross Unrealized Temporary Loss	405	490
Gross Unrealized OTTI Loss	167	206
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	37,203	35,055
U.S. Treasury and agency securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	41,931	43,928
Gross Unrealized Gain	3,352	2,251
Gross Unrealized Temporary Loss	474	1,056
Gross Unrealized OTTI Loss	0	0
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	44,809	45,123
CMBS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	15,541	16,115
Gross Unrealized Gain	549	605
Gross Unrealized Temporary Loss	98	170
Gross Unrealized OTTI Loss	0	0
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	15,992	16,550
ABS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	14,438	15,458
Gross Unrealized Gain	322	296
Gross Unrealized Temporary Loss	94	171
Gross Unrealized OTTI Loss	13	12
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	14,653	15,571
State and political subdivision securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	13,125	13,233
Gross Unrealized Gain	1,355	903
Gross Unrealized Temporary Loss	152	306
Gross Unrealized OTTI Loss	0	0
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,542 and $ 333,599, respectively; includes $4,152 and $4,005, respectively, relating to variable interest entities)	14,328	13,830
Equity Securities [Member]
Available-for-sale Securities [Abstract]
Cost or Amortized Cost	3,241	3,012
Gross Unrealized Gain	554	507
Gross Unrealized Temporary Loss	102	117
Gross Unrealized OTTI Loss	0	0
Equity securities	3,693	3,402
Common Stock [Member]
Available-for-sale Securities [Abstract]
Cost or Amortized Cost	2,079	1,927
Gross Unrealized Gain	470	431
Gross Unrealized Temporary Loss	19	5
Gross Unrealized OTTI Loss	0	0
Equity securities	2,530	2,353
Non-redeemable preferred stock [Member]
Available-for-sale Securities [Abstract]
Cost or Amortized Cost	1,162	1,085
Gross Unrealized Gain	84	76
Gross Unrealized Temporary Loss	83	112
Gross Unrealized OTTI Loss	0	0
Equity securities	$ 1,163	$ 1,049