Equity (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended								12 Months Ended				1 Months Ended	3 Months Ended	12 Months Ended		3 Months Ended
	Jan. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jan. 31, 2011 Y	Feb. 29, 2012 Repurchase of common stock	Dec. 31, 2010 Repurchase of common stock	Dec. 31, 2011 Repurchase of common stock	Feb. 17, 2012 Repurchase of common stock	Dec. 31, 2011 Dividend Paid
Equity
Dividends declared (in dollars per share)	$ 0.105	$ 0.015	$ 0.015	$ 0.015	$ 0.015	$ 0.015	$ 0.015	$ 0.015	$ 0.015	$ 0.06	$ 0.06	$ 0.06
Cumulative dividends declared										$ 10,097	$ 10,449	$ 10,308
Number of shares authorized to be repurchased under the current open-market stock repurchase program (in shares)													20,000,000
Repurchase of stock program, period (in years)													3
Statement
Number of shares repurchased under the current open-market stock repurchase program (in shares)														1,110,079		13,428,389
Payments for shares repurchased under the current open-market stock repurchase program (in dollars)										672,191				60,621		672,191
Remaining number of shares authorized to be repurchased under the current open-market stock repurchase program (in shares)																6,571,611	5,461,532
Fourth quarter dividend paid, per share (in dollars per share)															$ 0.015			$ 0.015
Dividend paid (in dollars)										$ 10,282	$ 10,413	$ 10,279						$ 2,447