Junior Subordinated Debt Securities Payable (Outstanding Junior Subordinated Debt Securities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Short-term Debt [Line Items]
Consolidated Balance Sheet Amount	$ 329,897	$ 329,897
6.20% Junior Subordinated Debt Securities [Member]
Short-term Debt [Line Items]
Date Issued	03/29/2004
Date Due	Mar. 29, 2034
Amount Issued	329,897
Consolidated Balance Sheet Amount	329,897	329,897
Fair Value	$ 326,313	$ 294,825
Subordinated debt, interest rate	6.20%