Cash, Cash Equivalents and Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Apr. 01, 2012
Effective maturity dates of available-for-sale investments
Less than 1 Year	$ 159,209
1-2 Years	76,422
2-3 Years	69,394
3-4 Years	17,712
4-5 Years	13,480
5-7 years	1,024
Fair Value, Total	337,241
Municipal bonds [Member]
Effective maturity dates of available-for-sale investments
Less than 1 Year	57,862
1-2 Years	21,567
2-3 Years	29,861
3-4 Years	10,489
4-5 Years	5,091
5-7 years	524
Fair Value, Total	125,394
Corporate bonds [Member]
Effective maturity dates of available-for-sale investments
Less than 1 Year	61,517
1-2 Years	37,014
2-3 Years	25,674
3-4 Years	4,868
4-5 Years	4,413
Fair Value, Total	133,486
Agency bonds [Member]
Effective maturity dates of available-for-sale investments
Less than 1 Year	27,298
1-2 Years	10,515
2-3 Years	2,101
3-4 Years	1,371
Fair Value, Total	41,285
Treasury bills [Member]
Effective maturity dates of available-for-sale investments
1-2 Years	999
Fair Value, Total	999
Sovereign Bonds [Member]
Effective maturity dates of available-for-sale investments
Less than 1 Year	6,222
1-2 Years	4,587
2-3 Years	8,732
3-4 Years	984
4-5 Years	3,976
Fair Value, Total	24,501
Covered bonds [Member]
Effective maturity dates of available-for-sale investments
Less than 1 Year	4,443
1-2 Years	1,740
Fair Value, Total	6,183
Asset-backed securities [Member]
Effective maturity dates of available-for-sale investments
Less than 1 Year	1,867
2-3 Years	3,026
5-7 years	500
Fair Value, Total	$ 5,393