Investments (Tables)

12 Months Ended

Dec. 31, 2020

Short-Term and Long-Term Investments [Table Text Block]

A summary of debt securities by major security type is as follows:


(in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2020
Debt securities - available-for-sale:
U.S. government and agency obligations	$	3,335	$	133	$	(3)	$	3,465
State and municipal obligations	6,893		435		—		7,328
Corporate obligations	18,886		863		(12)		19,737
U.S. agency mortgage-backed securities	6,849		245		(3)		7,091
Non-U.S. agency mortgage-backed securities	2,116		95		(4)		2,207
Total debt securities - available-for-sale	38,079		1,771		(22)		39,828
Debt securities - held-to-maturity:
U.S. government and agency obligations	420		6		—		426
State and municipal obligations	31		2		—		33
Corporate obligations	187		1		—		188
Total debt securities - held-to-maturity	638		9		—		647
Total debt securities	$	38,717	$	1,780	$	(22)	$	40,475
December 31, 2019
Debt securities - available-for-sale:
U.S. government and agency obligations	$	3,502	$	55	$	(4)	$	3,553
State and municipal obligations	5,680		251		(5)		5,926
Corporate obligations	17,910		343		(11)		18,242
U.S. agency mortgage-backed securities	6,425		109		(6)		6,528
Non-U.S. agency mortgage-backed securities	1,811		37		(3)		1,845
Total debt securities - available-for-sale	35,328		795		(29)		36,094
Debt securities - held-to-maturity:
U.S. government and agency obligations	402		2		—		404
State and municipal obligations	32		2		—		34
Corporate obligations	538		—		(1)		537
Total debt securities - held-to-maturity	972		4		(1)		975
Total debt securities	$	36,300	$	799	$	(30)	$	37,069

Investments by Contractual Maturity [Table Text Block]

The amortized cost and fair value of debt securities as of December 31, 2020, by contractual maturity, were as follows:


	Available-for-Sale				Held-to-Maturity
(in millions)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due in one year or less	$	2,951	$	2,966	$	348	$	349
Due after one year through five years	11,638		12,088		241		245
Due after five years through ten years	10,212		10,931		27		29
Due after ten years	4,313		4,545		22		24
U.S. agency mortgage-backed securities	6,849		7,091		—		—
Non-U.S. agency mortgage-backed securities	2,116		2,207		—		—
Total debt securities	$	38,079	$	39,828	$	638	$	647

Fair Value of Available-for-Sale Investments with Gross Unrealized Losses by Investment Type and Length of Time that Individual Securities have been in a Continuous Unrealized Loss Position [Table Text Block]

The fair value of available-for-sale debt securities with gross unrealized losses by major security type and length of time that individual securities have been in a continuous unrealized loss position were as follows:


	Less Than 12 Months				12 Months or Greater				Total
(in millions)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
December 31, 2020
U.S. government and agency obligations	$	346	$	(3)	$	—	$	—	$	346	$	(3)
Corporate obligations	1,273		(9)		456		(3)		1,729		(12)
U.S. agency mortgage-backed securities	601		(3)		—		—		601		(3)
Non-U.S. agency mortgage-backed securities	195		(1)		93		(3)		288		(4)
Total debt securities - available-for-sale	$	2,415	$	(16)	$	549	$	(6)	$	2,964	$	(22)
December 31, 2019
U.S. government and agency obligations	$	616	$	(4)	$	—	$	—	$	616	$	(4)
State and municipal obligations	440		(5)		—		—		440		(5)
Corporate obligations	1,903		(7)		740		(4)		2,643		(11)
U.S. agency mortgage-backed securities	657		(3)		333		(3)		990		(6)
Non-U.S. agency mortgage-backed securities	406		(3)		—		—		406		(3)
Total debt securities - available-for-sale	$	4,022	$	(22)	$	1,073	$	(7)	$	5,095	$	(29)