Stock Option and Stock Award Plans (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Feb. 28, 2015	Mar. 01, 2014	Mar. 02, 2013
Stock options and stock award Plans
Stock-based compensation costs	$ 23,390	$ 16,194	$ 17,717
Shares of common stock authorized under stock-based compensation plans	62,125
Maximum
Stock options and stock award Plans
Term of options	10 years
Stock options
Fair value assumptions
Expected stock price volatility (as a percent)	74.00%	85.00%	85.00%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Risk-free interest rate (as a percent)	1.70%	1.45%	0.71%
Expected option life	5 years 6 months	5 years 6 months	5 years 6 months
Additional General Disclosures
Weighted average fair value of options granted (in dollars per share)	$ 4.43	$ 1.91	$ 0.91
Cash received from stock option exercises	24,117	33,217	1,646
Income tax benefit from stock options	30,099	23,660	0
Total intrinsic value of options exercised	92,355	80,598	714
Vesting period	4 years
Shares
Outstanding at the beginning of the period (in shares)	55,966	81,000	73,798
Granted (in shares)	3,097	4,828	12,020
Exercised (in shares)	(16,485)	(26,873)	(1,535)
Cancelled (in shares)	(910)	(2,989)	(3,283)
Outstanding at the end of the period (in shares)	41,668	55,966	81,000
Vested or expected to vest at the end of the period (in shares)	40,422
Exercisable at the end of the period (in shares)	25,375
Weighted Average Exercise Price Per Share
Outstanding at the beginning of the period (in dollars per share)	$ 1.65	$ 1.48	$ 1.52
Granted (in dollars per share)	$ 7.04	$ 2.76	$ 1.32
Exercised (in dollars per share)	$ 1.46	$ 1.24	$ 1.06
Cancelled (in dollars per share)	$ 3.16	$ 2.46	$ 2.08
Outstanding at the end of the period (in dollars per share)	$ 2.09	$ 1.65	$ 1.48
Vested or expected to vest at the end of the period (in dollars per share)	$ 2.09
Exercisable at the end of the period (in dollars per share)	$ 1.74
Weighted Average Remaining Contractual Term
Outstanding at the end of the period	6 years 18 days
Vested or expected to vest at the end of the period	6 years 4 days
Exercisable at the end of the period	5 years 18 days
Aggregate Intrinsic Value
Outstanding at the end of the period	245,237
Vested or expected to vest at the end of the period	237,899
Exercisable at the end of the period	158,240
Unrecognized pre-tax compensation costs related to unvested stock options and restricted stock grants
Total unrecognized pre-tax compensation costs, net of forfeitures	17,871
Weighted-average period over which remaining share-based cost is expected to be recognized	2 years 6 months 29 days
Restricted stock
Additional General Disclosures
Total fair value of awards vested during the period	8,090	5,098	4,623
Unrecognized pre-tax compensation costs related to unvested stock options and restricted stock grants
Total unrecognized pre-tax compensation costs, net of forfeitures	19,371
Weighted-average period over which remaining share-based cost is expected to be recognized	2 years 1 month 2 days
Shares
Outstanding at the beginning of the period (in shares)	10,056	12,677	11,506
Granted (in shares)	3,303	2,743	5,450
Vested (in shares)	(5,239)	(4,152)	(3,917)
Cancelled (in shares)	(454)	(1,212)	(362)
Outstanding at the end of the period (in shares)	7,666	10,056	12,677
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 1.66	$ 1.25	$ 1.20
Granted (in dollars per share)	$ 7.01	$ 2.79	$ 1.31
Vested (in dollars per share)	$ 1.54	$ 1.23	$ 1.18
Cancelled (in dollars per share)	$ 5.00	$ 1.48	$ 1.26
Outstanding at the end of the period (in dollars per share)	$ 3.84	$ 1.66	$ 1.25
Restricted stock | Maximum
Additional General Disclosures
Vesting period	3 years
Performance based
Stock options and stock award Plans
Stock-based compensation costs	$ 1,769	$ 0	$ 0
1999 Plan
Stock options and stock award Plans
Shares of common stock authorized under stock-based compensation plans	10,000
2000 Plan
Stock options and stock award Plans
Shares of common stock reserved for the granting of stock options and other incentive awards	22,000
2001 Plan
Stock options and stock award Plans
Shares of common stock authorized under stock-based compensation plans	20,000
2004 Omnibus Equity Plan
Stock options and stock award Plans
Shares of common stock authorized under stock-based compensation plans	20,000
2006 Omnibus Equity Plan
Stock options and stock award Plans
Shares of common stock available for grant	50,000
2010 Omnibus Equity Plan
Stock options and stock award Plans
Shares of common stock available for grant	35,000
2012 Omnibus Equity Plan
Stock options and stock award Plans
Shares of common stock available for grant	28,500
2014 Omnibus Equity Plan
Stock options and stock award Plans
Shares of common stock available for grant	58,000
2014 Omnibus Equity Plan | Stock options | Maximum
Stock options and stock award Plans
Shares of common stock available for grant	25,000