Restricted Stock, Performance Share and Cash Awards - Schedule of Restricted Stock Awards Vesting Periods (Detail) - shares |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
Vesting Period [Line Items] | |||
Shares granted in the period | 394,975 | 376,541 | 369,975 |
Vesting Period One Year [Member] | |||
Vesting Period [Line Items] | |||
Shares granted in the period | 22,175 | 19,250 | 19,375 |
Vesting period, years | 1 year | ||
Vesting Period Three Years [Member] | |||
Vesting Period [Line Items] | |||
Shares granted in the period | 33,741 | ||
Vesting period, years | 3 years | ||
Vesting Period Four Years [Member] | |||
Vesting Period [Line Items] | |||
Shares granted in the period | 9,200 | 323,550 | 345,000 |
Vesting period, years | 4 years | ||
Vesting Period Five Years [Member] | |||
Vesting Period [Line Items] | |||
Shares granted in the period | 363,600 | 5,600 | |
Vesting period, years | 5 years |