Stockholders' Equity Dividends Declared (Details) - $ / shares	Feb. 02, 2018	Oct. 31, 2017	Aug. 02, 2017	May 04, 2017	Feb. 09, 2017
Dividends Declared [Abstract]
Dividend, declaration date	Feb. 02, 2018	Oct. 31, 2017	Aug. 02, 2017	May 04, 2017	Feb. 09, 2017
Dividend amount to be paid, per common share	$ 0.4050	$ 0.3950	$ 0.3850	$ 0.3750	$ 0.3650
Dividend, date of record	Feb. 22, 2018	Nov. 17, 2017	Aug. 14, 2017	May 19, 2017	Feb. 22, 2017
Dividend, date to be paid	Mar. 09, 2018	Dec. 05, 2017	Sep. 01, 2017	Jun. 02, 2017	Mar. 09, 2017