Dividends (Details Textual) - USD ($) $ / shares in Units, $ in Millions									1 Months Ended				3 Months Ended		9 Months Ended
	Sep. 02, 2016	Jul. 08, 2016	Jun. 02, 2016	Mar. 02, 2016	Dec. 11, 2015	Oct. 02, 2015	Jun. 10, 2015	Apr. 06, 2015	Aug. 30, 2016	Apr. 15, 2016	Nov. 17, 2015	Mar. 25, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Common Stock, Dividends, Per Share, Declared													$ 0.30	$ 0.20	$ 0.80	$ 0.60
Dividends		$ 1.5			$ 2.9	$ 1.2	$ 1.2	$ 1.2		$ 1.5					$ 1.8
Common Class A [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.20		$ 0.25	$ 0.25			$ 0.20		$ 0.30		$ 0.25	$ 0.20
Common Class B [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.20		$ 0.25	$ 0.25			$ 0.20		$ 0.30		$ 0.25	$ 0.20