Subsequent Events (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended		3 Months Ended	0 Months Ended
	Jan. 09, 2015	Oct. 10, 2014	Mar. 31, 2015	Apr. 10, 2015	Apr. 07, 2015	May 12, 2015
Subsequent Event [Line Items]
Debt Instrument, Face Amount					31.8
Common Class A One [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record	Jan. 25, 2015	Oct. 25, 2014
Common Stock, Dividends, Per Share, Declared	$ 0.29	$ 0.29
Dividends Payable, Date to be Paid	Feb. 05, 2015	Nov. 05, 2014
Common Class A Two [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record	Feb. 25, 2015	Nov. 25, 2014
Common Stock, Dividends, Per Share, Declared	$ 0.29	$ 0.29	$ 0.096666
Dividends Payable, Date to be Paid	Mar. 05, 2015	Dec. 05, 2014
Common Class B One [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record	Mar. 25, 2015	Dec. 25, 2014
Common Stock, Dividends, Per Share, Declared	$ 0.29	$ 0.29
Dividends Payable, Date to be Paid	Apr. 05, 2015	Jan. 05, 2015
Monthly Dividends [Member] | Common Class A One [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record	Jan. 25, 2015		Oct. 25, 2014
Common Stock, Dividends, Per Share, Declared	$ 0.096666		$ 0.096666	$ 0.29
Monthly Dividends [Member] | Common Class A Two [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record	Feb. 25, 2015		Nov. 25, 2014
Common Stock, Dividends, Per Share, Declared	$ 0.096666		$ 0.096666
Monthly Dividends [Member] | Common Class B One [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record	Mar. 25, 2015		Dec. 25, 2014
Common Stock, Dividends, Per Share, Declared	$ 0.096667		$ 0.096667	$ 0.29
Bank of America [Member]
Subsequent Event [Line Items]
Debt Instrument, Maturity Date, Description					loan matures on April 7, 2019, and contains a one-year extension option
Debt Instrument, Description of Variable Rate Basis					base rate plus 1.25% or LIBOR plus 2.25%
Subsequent Event [Member]
Subsequent Event [Line Items]
Purchase Price To Be Funded By Assumption Of Existing Loan						44.8
Expected Principal Amount In Secured Debt						31.9
Expects To Invest Of Equity						13.7
Maximum Purchase Price In Purchase Agreement						$ 21.8
Subsequent Event [Member] | Common Class A One [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record			Mar. 25, 2015	Apr. 25, 2015
Dividends Payable, Date to be Paid			Apr. 05, 2015	May 05, 2015
Subsequent Event [Member] | Common Class A Two [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record			Apr. 25, 2015	May 25, 2015
Dividends Payable, Date to be Paid			May 05, 2015	Jun. 05, 2015
Subsequent Event [Member] | Common Class B One [Member]
Subsequent Event [Line Items]
Dividends Payable, Date of Record				Jun. 25, 2015
Dividends Payable, Date to be Paid				Jul. 05, 2015