5. Investment Securities

Investment securities principally include debt securities the Company classifies as available-for-sale and carries at fair value on the Consolidated Balance Sheets, with unrealized gains (losses) recorded in Accumulated Other Comprehensive Loss (AOCI), net of income taxes. Realized gains and losses are recognized on a trade-date basis in the Consolidated Statements of Income upon disposition of the securities using the specific identification method.

The following is a summary of investment securities as of June 30, 2016 and December 31, 2015:

		2016								2015
					Gross		Gross		Estimated				Gross		Gross		Estimated
					Unrealized		Unrealized		Fair				Unrealized		Unrealized		Fair
Description of Securities (Millions)			Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
State and municipal obligations		$	2,530	$	72	$	―	$	2,602	$	2,813	$	85	$	(5)	$	2,893
U.S. Government agency
	obligations		2		―		―		2		2		―		―		2
U.S. Government treasury
	obligations		354		14		―		368		406		4		(1)		409
Corporate debt securities			26		1		―		27		29		1		―		30
Mortgage-backed securities ^(a)			111		5		―		116		117		4		―		121
Equity securities			1		―		―		1		1		―		―		1
Foreign government bonds and
	obligations		718		9		―		727		250		6		(1)		255
Other ^(b)			50		―		(1)		49		50		―		(2)		48
Total		$	3,792	$	101	$	(1)	$	3,892	$	3,668	$	100	$	(9)	$	3,759

Represents mortgage-backed securities guaranteed by Fannie Mae, Freddie Mac or Ginnie Mae.
Other comprises investments in various mutual funds.

The following table provides information about the Company’s investment securities with gross unrealized losses and the length of time that individual securities have been in a continuous unrealized loss position as of June 30, 2016 and December 31, 2015:

		2016								2015
		Less than 12 months				12 months or more				Less than 12 months				12 months or more
					Gross				Gross				Gross				Gross
Description of Securities (Millions)			Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
State and municipal obligations		$	―	$	―	$	―		―	$	100	$	(3)	$	13	$	(2)
U.S. Government treasury
	obligations		―		―		―		―		253		(1)		―		―
Foreign government bonds and
	obligations		―		―		―		―		99		(1)		―		―
Other			―		―		33		(1)		―		―		33		(2)
Total		$	―	$	―	$	33	$	(1)	$	452	$	(5)	$	46	$	(4)

The following table summarizes the gross unrealized losses due to temporary impairments by ratio of fair value to amortized cost as of June 30, 2016 and December 31, 2015:

	Less than 12 months					12 months or more					Total
Ratio of Fair Value to					Gross					Gross					Gross
Amortized Cost	Number of		Estimated		Unrealized	Number of		Estimated		Unrealized	Number of		Estimated		Unrealized
(Dollars in millions)	Securities		Fair Value		Losses	Securities		Fair Value		Losses	Securities		Fair Value		Losses
2016:
90%–100%	―	$	―	$	―	24	$	36	$	(1)	24	$	36	$	(1)
Less than 90%	―		―		―	―		―		―	―		―		―
Total as of June 30, 2016	―	$	―	$	―	24	$	36	$	(1)	24	$	36	$	(1)

2015:
90%–100%	52	$	450	$	(5)	15	$	37	$	(2)	67	$	487	$	(7)
Less than 90%	―		―		―	2		9		(2)	2		9		(2)
Total as of December 31, 2015	52	$	450	$	(5)	17	$	46	$	(4)	69	$	496	$	(9)

Overall, for the investment securities in gross unrealized loss positions (i) the Company does not intend to sell the investment securities, (ii) it is more likely than not that the Company will not be required to sell the investment securities before recovery of the unrealized losses, and (iii) the Company expects that the contractual principal and interest will be received on the investment securities. As a result, the Company recognized no other-than-temporary impairment during the periods presented.

Contractual maturities of investment securities with stated maturities as of June 30, 2016 were as follows:

				Estimated
(Millions)		Cost		Fair Value
Due within 1 year	$	815	$	817
Due after 1 year but within 5 years		172		177
Due after 5 years but within 10 years		413		435
Due after 10 years		2,341		2,413
Total^(a)	$	3,741	$	3,842

Balances primarily represent investments in state and municipal obligations, and foreign government bonds and obligations.

The expected payments on state and municipal obligations and mortgage-backed securities may not coincide with their contractual maturities because the issuers have the right to call or prepay certain obligations.