Summary of Stock Option Activity (Detail) - 2003 Plan - $ / shares |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2018 |
Dec. 31, 2017 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Number of Option, Beginning Balance | 24,875 | |
| Number of Option, Ending Balance | 24,875 | 24,875 |
| Number of Option, Exercisable, March 31, 2018 | 24,875 | |
| Weighted Average Exercise Price, Beginning Balance | $ 44.45 | |
| Weighted Average Exercise Price, Ending Balance | 44.45 | $ 44.45 |
| Weighted Average Exercise Price, Exercisable, March 31, 2018 | $ 44.45 | |
| Weighted Average Contractual Life | 2 years 2 months 30 days | 2 years 6 months 25 days |
| Weighted Average Contractual Life, Exercisable, March 31, 2018 | 2 years 2 months 30 days |
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|