Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) |
9 Months Ended | ||||
|---|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
||||
| Accounting Policies [Line Items] | |||||
| Payments to Acquire Short-term Investments | $ 44,088,000 | [1] | $ 0 | ||
| Short Term Investment Maximum Amount Per Institution | 250,000 | ||||
| Held-to-maturity Securities [Member] | |||||
| Accounting Policies [Line Items] | |||||
| Time Deposits, at Carrying Value | 44,100,000 | ||||
| Cash and Cash Equivalents [Member] | |||||
| Accounting Policies [Line Items] | |||||
| Time Deposits, at Carrying Value | $ 16,000,000 | ||||
| |||||
| X | ||||||||||
- Definition Accounting Policies [Line Items] No definition available.
|
| X | ||||||||||
- Definition The maximum amount to be held by each individual institution. No definition available.
|
| X | ||||||||||
- Definition The cash outflow for securities or other assets acquired, which qualify for treatment as an investing activity and are to be liquidated, if necessary, within the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the short-term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Any certificate of deposit or savings account held by a bank or other financial institution for a short-term specified period of time. Because of their short-term, time deposits are considered highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|