Income Taxes Statutory tax rate (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended			15 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate								$ 31,891	$ 15,627	$ 23,274
Dividend Income, Operating								(2,116)	(2,116)	(2,183)
Net Income (Loss) Attributable to Noncontrolling Interest								(7,766)	(7,766)	(7,248)
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance								6	(254)	(235)
Taxes, Other								141	306	189
Income tax expense/(benefit)	$ 4,837	$ 8,294	$ (2,629)	$ 11,654	$ 7,872	$ 2,539	$ 9,517	$ 22,156	$ 5,797	$ 13,797	$ (14,131)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate								35.00%	35.00%	35.00%