Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended								6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013 Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Fair Value, Inputs, Level 3 [Member]	Jun. 30, 2013 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Debt securities in government sponsored entities [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Debt securities in government sponsored entities [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Debt securities in government sponsored entities [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Debt securities in government sponsored entities [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Corporate debt securities [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Corporate debt securities [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 Corporate debt securities [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 Corporate debt securities [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 U.S. Treasury securities [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 U.S. Treasury securities [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2013 U.S. Treasury securities [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 30, 2012 U.S. Treasury securities [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]
Assets:
Money market funds (cash equivalents)			$ 594,536	$ 252,126	$ 594,536	$ 252,126
Investments, fair value disclosure												56,824	314,873	56,824	314,873	258,923	472,861	258,923	472,861	30,105	128,489	30,105	128,489
Deferred compensation plan assets			15,926	13,626			15,926	13,626
Total assets measured at fair value			956,314	1,181,975	624,641	380,615	331,673	801,360
Liabilities:
Acquisition related contingent consideration liability			60,102	12,519					60,102	60,102	12,519
Deferred compensation liability			13,834	12,071			13,834	12,071
Total liabilities measured at fair value			73,936	24,590			13,834	12,071		60,102	12,519
Change in estimated fair value of the contingent consideration liability
Balance as of beginning of period			60,102	12,519					12,519	60,102	12,519
Additional liability recorded as a result of current period acquisitions									57,284
Change in estimated fair value, recorded in acquisition related (gain) expense, net	5,262	(2,817)							(5,262)
Cash settlements									(4,439)
Balance as of end of period			$ 60,102	$ 12,519					$ 60,102	$ 60,102	$ 12,519