Charitable Contributions (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Charitable Contributions [Abstract]
Expense related to shareholder-designated charitable contribution program	$ 5.7	$ 4.1
Shareholder-designated contribution, diluted per share (in dollars per share)	$ 0.20	$ 0.08