Consolidated Statements of Operations (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements of Operations [Abstract]
Accretion of issuance cost of preferred dividends	$ 1,045	$ 4,489	$ 1,202

Value of accretion of temporary equity to its redemption value during the period. This item is an adjustment to net income necessary to derive net income apportioned to common stockholders and is to be distinguished from Temporary Equity, Accretion to Redemption Value (TemporaryEquityAccretionToRedemptionValue).

No definition available.

Name:	us-gaap_TemporaryEquityAccretionToRedemptionValueAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration