Cash, Cash Equivalents, and Short-Term Investments (Tables)
 3 Months Ended
Mar. 31, 2015
Cash, Cash Equivalents, and Short-term Investments [Abstract]  
Schedule of Cash, Cash Equivalents and Short-term Investments [Table Text Block])
The following table summarizes the Company’s cash, cash equivalents, and short-term investments as of March 31, 2015 (in thousands):
 
 
Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized
Losses
 
Estimated
Fair Value
Cash
$
251,867

 
$
—

 
$
—

 
$
251,867

Cash equivalents:
 

 
 

 
 

 
 

Money market funds
1,369

 
—

 
—

 
1,369

Commercial Paper
4,000

 
—

 
—

 
4,000

Total cash equivalents
5,369

 
—

 
—

 
5,369

Total cash and cash equivalents
257,236

 
—

 
—

 
257,236

Short-term investments:
 

 
 

 
 

 
 

Certificates of deposit
1,920

 
—

 
—

 
1,920

Commercial paper
8,992

 
—

 
—

 
8,992

Corporate notes and bonds
114,165

 
157

 
(86
)
 
114,236

Federal agency notes and bonds
29,072

 
35

 
(6
)
 
29,101

Time deposits
21,773

 
—

 
—

 
21,773

Municipal notes and bonds
65,363

 
98

 
(5
)
 
65,456

Total short-term investments
241,285

 
290

 
(97
)
 
241,478

Total cash, cash equivalents, and short-term investments
$
498,521

 
$
290

 
$
(97
)
 
$
498,714



The following table summarizes the Company’s cash, cash equivalents, and short-term investments as of December 31, 2014 (in thousands):
 
 
Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized
Losses
 
Estimated
Fair Value
Cash
$
353,187

 
$
—

 
$
—

 
$
353,187

Cash equivalents:
 

 
 

 
 

 
 

Money market funds
15,344

 
—

 
—

 
15,344

Total cash equivalents
15,344

 
—

 
—

 
15,344

Total cash and cash equivalents
368,531

 
—

 
—

 
368,531

Short-term investments:
 

 
 

 
 

 
 

Certificates of deposit
1,920

 
—

 
—

 
1,920

Commercial paper
1,996

 
—

 
—

 
1,996

Corporate notes and bonds
196,401

 
84

 
(371
)
 
196,114

Federal agency notes and bonds
51,987

 
13

 
(44
)
 
51,956

Time deposits
26,395

 
—

 
—

 
26,395

Municipal notes and bonds
74,639

 
128

 
(18
)
 
74,749

Total short-term investments
353,338

 
225

 
(433
)
 
353,130

Total cash, cash equivalents, and short-term investments
$
721,869

 
$
225

 
$
(433
)
 
$
721,661
Available-for-sale Securities Continuous Unrealized Loss Position, Fair Value [Table Text Block]
The following table summarizes the fair value and gross unrealized losses related to the Company’s short-term investments, aggregated by investment category that have been in a continuous unrealized loss position for less than twelve months, at March 31, 2015 (in thousands):
 
Less Than 12 months
 
 
 
 
Fair
Value
 
Gross
Unrealized
Losses
Corporate notes and bonds
$
32,411

 
$
(83
)
Federal agency notes and bonds
12,009

 
(6
)
Municipal notes and bonds
6,542

 
(5
)
Total
$
50,962

 
$
(94
)

The following table summarizes the fair value and gross unrealized losses related to the Company’s short-term investments, aggregated by investment category that have been in a continuous unrealized loss position for greater than twelve months, at March 31, 2015 (in thousands):
 
Greater Than 12 months
 
 
 
 
Fair
Value
 
Gross
Unrealized
Losses
Corporate notes and bonds
$
1,026

 
$
(3
)
Total
$
1,026

 
$
(3
)
Investments Classified by Contractual Maturity Date [Table Text Block]
The following table summarizes the cost and estimated fair value of the Company’s short-term investments by contractual maturity at March 31, 2015 (in thousands):
 
Cost
 
Fair
Value
Due within one year
$
152,265

 
$
152,363

Due in one year to two years
66,507

 
66,541

Due after two years
22,513

 
22,574

Total
$
241,285

 
$
241,478