Subsequent Events (Details Textual) (USD $)	1 Months Ended
	Mar. 31, 2013	Oct. 31, 2013 Subsequent Event [Member] Senior Notes [Member]	Oct. 31, 2013 Subsequent Event [Member] Series A Preferred Stock [Member]
Stock Issued For Underwritten Public Offering Shares			3,800,000
Stock Issued During Period, Shares, New Issues			400,000
Shares Issued, Price Per Share			$ 25.0611
Proceeds from Issuance Initial Public Offering	$ 299,700,000		$ 91,700,000
Other Underwriting Expense			3,500,000
Line Of Credit Facility Private Offering		100,000,000
Exchange Rate Of Common Stock Or Exchangeable Senior Notes Per Share		$ 79.6020
Line of Credit Facility, Periodic Payment, Principal		$ 1,000
Senior Notes Initial Exchange Price Per Share		$ 12.56