Condensed Consolidated Statements of Redeemable Preferred Stock and Equity (Parenthetical) (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Statement - Condensed Consolidated Statements of Redeemable Preferred Stock and Equity (Parenthetical) (Unaudited) [Line Items]
Issuance of common stock in initial public offering, issue cost	$ 8,892