|
Incentive Award Plan and Stock Option Plan - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified |
3 Months Ended | 6 Months Ended | 6 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Jun. 30, 2014
|
Jun. 30, 2014
General and Administrative Expense
|
Jun. 30, 2013
General and Administrative Expense
|
Jun. 30, 2014
General and Administrative Expense
|
Jun. 30, 2013
General and Administrative Expense
|
Jun. 30, 2014
Non-vested shares of restricted stock
|
Jun. 30, 2014
Non-vested shares of restricted stock
Directors Officers And Employees
|
Jun. 30, 2014
Performance Shares
|
Dec. 31, 2013
Performance Shares
|
Jun. 30, 2014
Performance Shares
Minimum
|
Jun. 30, 2014
Performance Shares
Maximum
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||||||||
| Number of shares authorized under plan (in shares) | 2,600,000 | ||||||||||
| Grants in period (in shares) | 400,000 | ||||||||||
| Deferred compensation expense | $ 3.8 | ||||||||||
| Outstanding non vested restricted shares (in shares) | 2,000,000 | ||||||||||
| Shares of common stock available for issuance (in shares) | 242,883 | ||||||||||
| Multiplier for shares granted | 0.00% | 250.00% | |||||||||
| Stock-based compensation expense | 3.0 | 1.8 | 5.5 | 3.6 | 3.3 | ||||||
| Potential grants in period based on total shareholder return (in shares) | 1,100,000 | ||||||||||
| Dividend rights accrued | 0.4 | ||||||||||
| Unamortized stock based compensation expense | $ 17.4 | $ 15.6 | |||||||||