Fair Value Measurements (Recurring Basis) (Details) - USD ($) $ in Thousands	Oct. 31, 2015	Jan. 31, 2015
Auction-rate securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Estimated Fair Value	$ 7,300	$ 7,368
Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities (including mutual funds)	13,358	14,261
Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Totals	20,658	21,629
Fair Value Measurements, Recurring [Member] | Auction-rate securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Estimated Fair Value	7,300	7,368
Fair Value Measurements, Recurring [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities (including mutual funds)	13,358	14,261
Fair Value Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Totals	13,358	14,261
Fair Value Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Auction-rate securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Estimated Fair Value	0	0
Fair Value Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities (including mutual funds)	13,358	14,261
Fair Value Measurements, Recurring [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Totals	182	182
Fair Value Measurements, Recurring [Member] | Significant Observable Inputs (Level 2) [Member] | Auction-rate securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Estimated Fair Value	182	182
Fair Value Measurements, Recurring [Member] | Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities (including mutual funds)	0	0
Fair Value Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Totals	7,118	7,186
Fair Value Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Auction-rate securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Estimated Fair Value	7,118	7,186
Fair Value Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities (including mutual funds)	$ 0	$ 0