Equity Incentive Programs (Schedule of Restricted Stock and Restricted Stock Unit Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	$ 15.9
Estimated Future Expense in Year One
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	10.0
Estimated Future Expense in Year Two
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	5.2
Estimated Future Expense in Year Three
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	$ 0.7
Restricted Stock and Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of days dividends will be paid after vesting, maximum	45 days
Weighted- Average Grant Date Fair Value Per Share
Compensation expense recognized	$ 14.7	$ 15.5	$ 14.4
Total future compensation expense	15.9
Restricted Stock and Restricted Stock Units (RSUs) | Estimated Future Expense in Year One
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	10.0
Restricted Stock and Restricted Stock Units (RSUs) | Estimated Future Expense in Year Two
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	5.2
Restricted Stock and Restricted Stock Units (RSUs) | Estimated Future Expense in Year Three
Weighted- Average Grant Date Fair Value Per Share
Total future compensation expense	$ 0.7
Restricted Stock
Shares
Nonvested at beginning of year, (in shares)	2,470,158
Granted, Units (in shares)	668,359
Vested (in shares)	(650,320)
Forfeited, Units (in shares)	(152,281)
Nonvested at end of year, (in shares)	2,335,916	2,470,158
Weighted- Average Grant Date Fair Value Per Share
Nonvested, beginning of year, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	$ 16.95
Granted, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	22.54
Vested, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	21.26
Forfeited, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	16.84
Nonvested, end of year, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	$ 17.36	$ 16.95
Nonvested, Weighted- Average Remaining Contractual Term (Years)	1 year	1 year 2 months
Restricted Stock Units (RSUs)
Shares
Nonvested at beginning of year, (in shares)	114,942
Granted, Units (in shares)	18,586
Vested (in shares)	(19,510)
Forfeited, Units (in shares)	(6,926)
Nonvested at end of year, (in shares)	107,092	114,942
Weighted- Average Grant Date Fair Value Per Share
Nonvested, beginning of year, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	$ 16.68
Granted, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	22.60
Vested, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	23.11
Forfeited, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	14.19
Nonvested, end of year, Weighted-Average Grant Date Fair Value Per Share (in dollars per share)	$ 16.70	$ 16.68
Nonvested, Weighted- Average Remaining Contractual Term (Years)	9 months	1 year 4 months