Net Income per Share (Net Income Per Basic and Diluted Share) (Parentheticals) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Income per Share [Abstract]
Estimated tax on interest expense on convertible notes	$ 25	$ 3,000	$ 2,700