Shareholders' Equity - Cash Dividends Declared Per Common Share (Details) - $ / shares	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2012	Dec. 31, 2016	Dec. 31, 2015
Disclosure Shareholders Equity [Abstract]
Quarterly dividend declared and paid per common share	$ 0.55	$ 0.53	$ 2.2	$ 2.12