Shareholders' Equity (Aggregate Fair Values Assigned to Each Component of Tangible Equity Units Offering) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2010	Dec. 07, 2010
Shareholders' Equity [Line Items]
Units issued (in shares)		4,600	[1]
Unit price (in usd per share)		$ 50.00
Gross proceeds		$ 230,000
Issuance costs, including discount		7,353
Carrying value of tangible equity units, net proceeds	222,647
Equity Component [Member]
Shareholders' Equity [Line Items]
Units issued (in shares)		4,600	[1]
Unit price (in usd per share)		$ 40.271818
Gross proceeds		185,250
Issuance costs, including discount		5,934
Carrying value of tangible equity units, net proceeds	179,316
Debt Component [Member]
Shareholders' Equity [Line Items]
Units issued (in shares)		4,600	[1]
Unit price (in usd per share)		$ 9.728182
Gross proceeds		44,750
Issuance costs, including discount		1,419
Carrying value of tangible equity units, net proceeds	43,331
Other Borrowings [Member]
Shareholders' Equity [Line Items]
Carrying value of tangible equity units, net proceeds	43,331
Other Borrowings [Member] | Equity Component [Member]
Shareholders' Equity [Line Items]
Carrying value of tangible equity units, net proceeds	0
Other Borrowings [Member] | Debt Component [Member]
Shareholders' Equity [Line Items]
Carrying value of tangible equity units, net proceeds	43,331
Surplus [Member]
Shareholders' Equity [Line Items]
Carrying value of tangible equity units, net proceeds	179,316
Surplus [Member] | Equity Component [Member]
Shareholders' Equity [Line Items]
Carrying value of tangible equity units, net proceeds	179,316
Surplus [Member] | Debt Component [Member]
Shareholders' Equity [Line Items]
Carrying value of tangible equity units, net proceeds	$ 0

[1] TEUs consist of two components: one unit of the equity component and one unit of the debt component.