Summary of Significant Accounting Policies (Details)	12 Months Ended		1 Months Ended
	Dec. 31, 2011 D	Jan. 18, 2011	Dec. 31, 2010 Numerator	Dec. 31, 2010 Denominator
Basis of presentation
Stock split conversion ratio			2	1
Number of additional shares of common stock distributed for each share held (in shares per share)		1
Cash and cash equivalents
Maximum term of original or remaining maturity to classify highly liquid investments as cash and cash equivalents (in days)	90