Subsequent Events - (Details) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2015
Subsequent Event [Line Items]
Proceeds from Issuance of Common Stock	$ 0	$ 0	$ 594,379,000
Class A Common Stock Offering [Member]
Subsequent Event [Line Items]
Proceeds from Issuance of Common Stock				367,000,000
Common Class A [Member]
Subsequent Event [Line Items]
Number of shares of stock issued			22,144,200
Common Class A [Member] | Class A Common Stock Offering [Member]
Subsequent Event [Line Items]
Number of shares of stock issued				9,430,000
Gross Offering Price Per Share Of Stock Issued				$ 38.90
Series A Community Reinvestment Act Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Stock, Redemption Amount	10,000,000
Series A Community Reinvestment Act Preferred Stock [Member] | Notice of Redemption [Member]
Subsequent Event [Line Items]
Preferred Stock, Redemption Amount				$ 27,000,000