Subsequent Events (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	May 07, 2015	Mar. 31, 2015
Subsequent Event [Line Items]
Remaining shares authorized to be repurchased through stock repurchase program		2,500,000
Subsequent Event
Subsequent Event [Line Items]
Remaining shares authorized to be repurchased through stock repurchase program	20,000,000
Subsequent Event | Micrel Incorporated [Member]
Subsequent Event [Line Items]
Acquisition price per share	$ 14.00
Total equity value	$ 839
Total enterprise value	744
Cash and short term investments acquired	$ 95.0