Debt - Revolving Credit Facility (Details) - Line of Credit [Member] |
3 Months Ended | |
|---|---|---|
|
Apr. 30, 2016
USD ($)
|
May. 20, 2015
USD ($)
|
|
| Debt Instrument [Line Items] | ||
| Maximum borrowing capacity | $ 250,000,000.0 | |
| Amount outstanding | $ 0 | |
| Remaining borrowing capacity | $ 247,600,000 | |
| Fixed charge ratio, Numerator | 1.0 | |
| Fixed Charge Ratio, Denominator | 1.0 | |
| Percent of borrowing base in fixed charge coverage ratio restriction | 10.00% |