Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 16, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Subsequent Event [Line Items]
Dividends declared, amount per common share		$ 0.17	$ 0.17	$ 0.15	$ 0.15	$ 0.13	$ 0.13
Subsequent event
Subsequent Event [Line Items]
Dividends declared, amount per common share	$ 0.17
Business Combination, Pending Acquisition - Estimated Gross Amount of Consideration to Transfer	$ 190