Declaration of Dividends (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Dividends Payable [Line Items]
Dividends on common stock (in dollars per share)	$ 0.09	$ 0.08
Dividends payable recorded date	Mar. 13, 2015
Dividends payable declared date	Jan. 21, 2015
Dividends payable, date to be paid	Apr. 01, 2015
Series C Preferred Stock [Member]
Dividends Payable [Line Items]
Dividends payable recorded date	Apr. 01, 2015
Dividends payable declared date	Jan. 21, 2015
Dividends payable, date to be paid	Apr. 15, 2015
Preferred stock dividend rate (in hundredth)	1.00%