Available-for-Sale Marketable Securities - Schedule of Fair Values and Continuous Unrealized Loss Positions of Available-for-Sale Marketable Securities (Detail) - USD ($)
$ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value |
$ 17,668
|
$ 57,132
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses |
(9)
|
(40)
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value |
0
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses |
0
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, Fair Value |
17,668
|
57,132
|
| Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses |
(9)
|
(40)
|
| U.S. Treasury Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value |
2,522
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses |
(1)
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value |
0
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses |
0
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Fair Value |
2,522
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses |
(1)
|
|
| Money Market Funds [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value |
|
30,985
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses |
|
(31)
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value |
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses |
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, Fair Value |
|
30,985
|
| Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses |
|
(31)
|
| Corporate Bonds [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value |
9,919
|
14,187
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses |
(6)
|
(6)
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value |
0
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses |
0
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, Fair Value |
9,919
|
14,187
|
| Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses |
(6)
|
(6)
|
| Commercial Paper [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value |
5,227
|
11,960
|
| Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses |
(2)
|
(3)
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value |
0
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses |
0
|
0
|
| Available-for-sale marketable securities, continuous unrealized loss position, Fair Value |
5,227
|
11,960
|
| Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses |
$ (2)
|
$ (3)
|