Summary of Significant Accounting Policies (Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Feb. 03, 2018	Jan. 28, 2017
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Significant Accounting Policies [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 117,373	$ 46
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	177	0
Held-to-maturity Securities, Fair Value	117,196	45
Corporate Bond Securities [Member] | Other Long-term Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Significant Accounting Policies [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	25,465	6
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	170	0
Held-to-maturity Securities, Fair Value	25,295	6
Municipal Bonds [Member]
Significant Accounting Policies [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	131,958	78
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	177	0
Held-to-maturity Securities, Fair Value	131,781	78
Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Significant Accounting Policies [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	14,585	32
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	0
Held-to-maturity Securities, Fair Value	14,585	32
Municipal Bonds [Member] | Other Long-term Investments [Member]
Significant Accounting Policies [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	27,702	11
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	172	0
Held-to-maturity Securities, Fair Value	27,530	11
Municipal Bonds [Member] | Other Long-term Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Significant Accounting Policies [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	2,237	4
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	2	0
Held-to-maturity Securities, Fair Value	$ 2,235	$ 4