Dividends on Common Stock (Details Textual) - $ / shares	3 Months Ended						6 Months Ended
	Jun. 30, 2018		Mar. 31, 2018	Jun. 30, 2017	[1]	Mar. 31, 2017	Jun. 30, 2018	[1]	Jun. 30, 2017	[1]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.15		$ 0.15
Common Stock, Dividends, Per Share, Declared	$ 0.15	[1]		$ 0.125		$ 0.125	$ 0.30		$ 0.25

[1] Share and per share data has been adjusted to reflect a 2-for-1 stock split on July 12, 2018.