Statement of Stockholders' Equity (Parentheticals) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Stockholders Equity [Abstract]
Dividends Declared Per Common Share	$ 0.42	$ 0.54	$ 0.56	$ 1.92	$ 2.16	$ 1.395