Equity Equity, Textuals (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011
Dividends declared per share	$ 0	$ 0
Dividends, Common Stock, Cash	$ 12,700,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	190,100,000
Payments for Repurchase of Common Stock	1,708,000	75,106,000
Business Acquisition, Percentage of Voting Interests Acquired	10.00%			70.00%
Payments to Acquire Additional Interest in Subsidiaries	$ (8,333,000)		$ 0
Treasury Stock, Shares, Acquired		0
Noncontrolling Interest, Ownership Percentage by Parent	80.00%