Summary of Significant Accounting Policies - Debt (Details) - Senior Notes [Member] - USD ($) |
Feb. 29, 2016 |
Feb. 28, 2015 |
Jan. 21, 2011 |
|---|---|---|---|
| Unsecured Senior Notes Due March 31, 2018 [Member] | |||
| Debt Instrument [Line Items] | |||
| Fair value of notes | $ 154,665,000 | $ 164,418,000 | |
| Debt Instrument, Annual Principal Payment | 14,300,000 | ||
| Debt instrument, face amount | $ 100,000,000 | ||
| Unsecured Senior Notes Due January 2021 [Member] | |||
| Debt Instrument [Line Items] | |||
| Debt instrument, face amount | $ 125,000,000 |