|
Schedule of Investment Securities (Detail) (USD $)
In Thousands, unless otherwise specified |
Sep. 30, 2014
|
Dec. 31, 2013
|
|---|---|---|
| Schedule of Available-for-sale Securities [Line Items] | ||
| Amortized cost | $ 250,659 | $ 254,359 |
| Gross unrealized gains | 130 | 156 |
| Gross unrealized losses | (57) | (127) |
| Fair value (net carrying amount) | 250,732 | 254,388 |
|
Domestic and foreign corporate bonds
|
||
| Schedule of Available-for-sale Securities [Line Items] | ||
| Amortized cost | 199,454 | 221,418 |
| Gross unrealized gains | 119 | 140 |
| Gross unrealized losses | (48) | (124) |
| Fair value (net carrying amount) | 199,525 | 221,434 |
|
Commercial paper
|
||
| Schedule of Available-for-sale Securities [Line Items] | ||
| Amortized cost | 51,205 | 32,941 |
| Gross unrealized gains | 11 | 16 |
| Gross unrealized losses | (9) | (3) |
| Fair value (net carrying amount) | $ 51,207 | $ 32,954 |