Shareholder Rights Plan (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Feb. 08, 2008
Shareholder Rights Plan [Abstract]
Number of rights granted per share owned (in shares)		1
Price per half share of common stock (in dollars per share)		$ 40
Alternate price per half share of common stock (in dollars oer share)		$ 80
Beneficial ownership that triggers the shareholder rights, Minimum (in hundredths)		15.00%
Redemption price of rights (in dollars per right)		$ 0.001
Time period for independent directors to review the Shareholders' Rights Plan	3 years