Available-for-Sale Marketable Securities - Summary of Available-for-Sale Marketable Securities by Major Type of Security (Detail) - USD ($)
$ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
$ 46,181
|
$ 91,675
|
| Gross Unrealized Gains |
12
|
5
|
| Gross Unrealized Losses |
(9)
|
(40)
|
| Estimated Fair Value |
46,184
|
91,640
|
| Money Market Funds [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
8,268
|
42,017
|
| Gross Unrealized Gains |
8
|
|
| Gross Unrealized Losses |
|
(31)
|
| Estimated Fair Value |
8,276
|
41,986
|
| U.S. Treasury Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
2,523
|
2,528
|
| Gross Unrealized Losses |
(1)
|
|
| Estimated Fair Value |
2,522
|
2,528
|
| US Government Corporations and Agencies Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
3,501
|
13,492
|
| Gross Unrealized Gains |
1
|
4
|
| Estimated Fair Value |
3,502
|
13,496
|
| Corporate Bonds [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
16,683
|
14,194
|
| Gross Unrealized Losses |
(6)
|
(6)
|
| Estimated Fair Value |
16,677
|
14,188
|
| Commercial Paper [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
15,206
|
19,444
|
| Gross Unrealized Gains |
3
|
1
|
| Gross Unrealized Losses |
(2)
|
(3)
|
| Estimated Fair Value |
$ 15,207
|
$ 19,442
|