Employee Benefit Plans (Options) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of year	1,968,607
Granted	0	0	0
Exercised	(428,938)	(454,602)	(479,831)
Forfeited	(13,926)
Outstanding, end of year	1,525,743	1,968,607
Exercisable, end of year	1,525,743
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning of year - weighted average exercise price	$ 16.86
Exercised - weighted average exercise price	(15.24)
Forfeited - weighted average exercise price	(10.31)
Outstanding, end of year - weighted average exercise price	17.36	$ 16.86
Exercisable, end of year - weighted average exercise price	$ 17.36
Additional disclosures:
Outstanding, end of year, weighted average contractual term	3 years 3 months 18 days
Exercisable, end of year, weighted average contractual term	3 years 3 months 18 days
Outstanding, end of year, aggregate intrinsic value	$ 55.5
Exercisable, end of year, aggregate intrinsic value	$ 55.5
Weighted average grant date fair value	$ 0	$ 0.00	$ 0.00
Total intrinsic value of options exercised	$ 10.8	$ 12.0	$ 10.3
Proceeds from option exercises	$ 10.3	$ 10.1	$ 10.0
Stock options
Additional disclosures:
Life of award	10 years
Vesting period	4 years