v3.8.0.1
Short-term and Long-term Investments, Restricted Deposits (Tables)
 12 Months Ended
Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]  
Short-term and long-term investments and restricted deposits by investment type
Short-term and long-term investments and restricted deposits by investment type consist of the following ($ in millions):
 
December 31, 2017
 
December 31, 2016
 
Amortized
Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized Losses
 
Fair
Value
 
Amortized
Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized Losses
 
Fair
Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies
$
311

 
$
—

 
$
(2
)
 
$
309

 
$
364

 
$
—

 
$
(1
)
 
$
363

Corporate securities
2,208

 
12

 
(10
)
 
2,210

 
1,933

 
12

 
(13
)
 
1,932

Restricted certificates of deposit
4

 
—

 
—

 
4

 
5

 
—

 
—

 
5

Restricted cash equivalents
17

 
—

 
—

 
17

 
6

 
—

 
—

 
6

Municipal securities
2,085

 
12

 
(10
)
 
2,087

 
1,767

 
1

 
(35
)
 
1,733

Asset-backed securities
437

 
1

 
(1
)
 
437

 
317

 
1

 
(1
)
 
317

Residential mortgage-backed securities
337

 
1

 
(6
)
 
332

 
219

 
1

 
(5
)
 
215

Commercial mortgage- backed securities
272

 
1

 
(2
)
 
271

 
343

 
—

 
(5
)
 
338

Equity method investments
176

 
—

 
—

 
176

 
163

 
—

 
—

 
163

Life insurance contracts
135

 
—

 
—

 
135

 
116

 
—

 
—

 
116

Total
$
5,982

 
$
27

 
$
(31
)
 
$
5,978

 
$
5,233

 
$
15

 
$
(60
)
 
$
5,188
Schedule of available-for-sale investments in a continuous unrealized loss position
The 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 were as follows ($ in millions):
 
December 31, 2017
 
December 31, 2016
 
Less Than 12 Months
 
12 Months or More
 
Less Than 12 Months
 
12 Months or More
 
Unrealized Losses
 
Fair
Value
 
Unrealized Losses
 
Fair
Value
 
Unrealized Losses
 
Fair
Value
 
Unrealized Losses
 
Fair
Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies
$
(1
)
 
$
222

 
$
(1
)
 
$
79

 
$
(1
)
 
$
215

 
$
—

 
$
2

Corporate securities
(6
)
 
1,044

 
(4
)
 
185

 
(12
)
 
1,020

 
(1
)
 
39

Municipal securities
(7
)
 
943

 
(3
)
 
175

 
(35
)
 
1,423

 
—

 
30

Asset-backed securities
(1
)
 
228

 
—

 
28

 
(1
)
 
101

 
—

 
18

Residential mortgage- backed securities
(1
)
 
109

 
(5
)
 
171

 
(5
)
 
188

 
—

 
—

Commercial mortgage- backed securities
(1
)
 
112

 
(1
)
 
51

 
(5
)
 
271

 
—

 
—

Total
$
(17
)
 
$
2,658

 
$
(14
)
 
$
689

 
$
(59
)
 
$
3,218

 
$
(1
)
 
$
89
Contractual maturities of short-term and long-term investments and restricted deposits
The contractual maturities of short-term and long-term investments and restricted deposits are as follows ($ in millions):
 
December 31, 2017
 
December 31, 2016
 
Investments
 
Restricted Deposits
 
Investments
 
Restricted Deposits
 
Amortized
Cost
 
Fair
Value
 
Amortized
Cost
 
Fair
Value
 
Amortized
Cost
 
Fair
Value
 
Amortized
Cost
 
Fair
Value
One year or less
$
474

 
$
474

 
$
48

 
$
47

 
$
500

 
$
500

 
$
91

 
$
91

One year through five years
2,424

 
2,420

 
88

 
88

 
1,982

 
1,974

 
47

 
47

Five years through ten years
1,773

 
1,779

 
—

 
—

 
1,101

 
1,089

 
—

 
—

Greater than ten years
129

 
130

 
—

 
—

 
633

 
617

 
—

 
—

Asset-backed securities
1,046

 
1,040

 
—

 
—

 
879

 
870

 
—

 
—

Total
$
5,846

 
$
5,843

 
$
136

 
$
135

 
$
5,095

 
$
5,050

 
$
138

 
$
138