Share-Based Compensation - Activity in Company's Plan - Long Term Incentive Plan (Detail) - Long Term Incentive Plan Stock Option [Member] - USD ($)
$ / shares in Units, $ in Thousands |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Outstanding at January 1, 2016, Number of Shares |
56,250
|
|
|
| Granted, Number of Shares |
0
|
10,500
|
35,500
|
| Exercised, Number of Shares |
(500)
|
0
|
(1,250)
|
| Forfeited, Number of Shares |
(3,000)
|
|
|
| Outstanding (vested and expected to vest) at December 31, 2016, Number of Shares |
52,750
|
|
|
| Exercisable at December 31, 2016, Number of Shares |
39,875
|
|
|
| Outstanding at January 1, 2016, Weighted Average Exercise Price per Share |
$ 55.30
|
|
|
| Granted, Weighted Average Exercise Price per Share |
0
|
|
|
| Exercised, Weighted Average Exercise Price per Share |
37.4
|
|
|
| Forfeited, Weighted Average Exercise Price per Share |
71.62
|
|
|
| Outstanding (vested and expected to vest) at December 31, 2016, Weighted Average Exercise Price per Share |
54.54
|
|
|
| Exercisable at December 31, 2016, Weighted Average Exercise Price per Share |
$ 55.42
|
|
|
| Outstanding (vested and expected to vest) at December 31, 2016, Weighted Average Remaining Contractual Term |
5 years 9 months 18 days
|
|
|
| Exercisable at December 31, 2016, Weighted Average Remaining Contractual Term |
7 years
|
|
|
| Outstanding (vested and expected to vest) at December 31, 2016, Aggregate Intrinsic Value |
$ 17
|
|
|
| Exercisable at December 31, 2016, Aggregate Intrinsic Value |
$ 19
|
|
|