Employee Benefit Plans (Narrative) (Details) (USD $)	12 Months Ended
	Jan. 31, 2012 years	Jan. 31, 2011	Jan. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grant	4,000,000
Number of shares available for grant	3,200,000
Stock-based compensation expense	$ 10,699,000	$ 9,887,000	$ 11,225,000
Stock-based compensation expense, related income tax benefits	2,900,000	2,800,000	2,600,000
Cash received from equity-based incentives exercised	35,100,000	5,000,000	38,000,000
Tax deduction from the exercise of equity-based incentives	2,200,000	1,100,000	1,900,000
Awards vesting period, maximum (in years)	four
Awards vesting period, minimum (in years)	one
RSU compensation expense	9,400,000	7,500,000	7,400,000
Total fair value of equity instruments other than options which vested	7,900,000	7,100,000	9,400,000
Stock-based compensation expense for the vesting of MV Stock-settled SARS and MVOs	1,300,000	2,400,000	3,800,000
Intrinsic value of MV Stock-settled SARs, MVO and stock option awards exercised	14,100,000	5,300,000	19,700,000
Total fair value of MV Stock-settled SARs and MVOs vested	1,500,000	4,500,000	1,900,000
Equity instruments other than options, granted during period	272,949
Weighted-average estimated fair value	$ 48.53
Purchase price as a percentage of the market value	85.00%
Maximum annual fair market value per employee	25,000
Common stock shares authorized under ESPP	1,000,000
Common stock shares issued to ESPP	472,442
Maximum percentage of participant's deferrals matched by Company	6.00%
Percentage of employer's matching contribution	50.00%
Number of common stock shares held by the Company's 401(k) Savings Plan	157,722	184,699
Company's contribution to 401(k)	2,500,000	2,300,000	100,000
Contractual term (in years)	10
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period, maximum (in years)	four
Awards vesting period, minimum (in years)	three
Unrecognized stock-based compensation expense	19,900,000
Unrecognized stock-based compensation expense, weighted average period of recognition (in years)	3
Remaining weighted average period (in years)	2
MV Stock-settled SARs, MVOs And Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period, maximum (in years)	four
Awards vesting period, minimum (in years)	three
Unrecognized stock-based compensation expense	$ 2,000,000
Unrecognized stock-based compensation expense, weighted average period of recognition (in years)	3
Remaining weighted average period (in years)	1
Equity instruments other than options, granted during period	12,882	17,799
Weighted-average estimated fair value	$ 10.78	$ 7.97
Contractual term (in years)	10
Retirement Savings Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
401(k) Savings Plan vesting period (years)	four