Shareholders' Equity (Aggregate Fair Values Assigned to Each Component of Tangible Equity Units Offering) (Details) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2010 USD ($)	Dec. 07, 2010 USD ($) $ / shares shares
Class of Stock [Line Items]
Units issued | shares	[1]		4,600
Unit price | $ / shares			$ 50.00
Gross proceeds			$ 230,000
Issuance costs, including discount			$ 7,353
Net proceeds		$ 222,647
Tangible Equity Unit Components			2
Equity Component
Class of Stock [Line Items]
Units issued | shares	[1]		4,600
Unit price | $ / shares			$ 40.271818
Gross proceeds			$ 185,250
Issuance costs, including discount			$ 5,934
Net proceeds		179,316
Tangible Equity Unit Components			1
Debt Component
Class of Stock [Line Items]
Units issued | shares	[1]		4,600
Unit price | $ / shares			$ 9.728182
Gross proceeds			$ 44,750
Issuance costs, including discount			$ 1,419
Net proceeds		43,331
Tangible Equity Unit Components			1
Other borrowings
Class of Stock [Line Items]
Net proceeds		43,331
Other borrowings | Equity Component
Class of Stock [Line Items]
Net proceeds		0
Other borrowings | Debt Component
Class of Stock [Line Items]
Net proceeds		43,331
Surplus
Class of Stock [Line Items]
Net proceeds		179,316
Surplus | Equity Component
Class of Stock [Line Items]
Net proceeds		179,316
Surplus | Debt Component
Class of Stock [Line Items]
Net proceeds		$ 0

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