Stock Compensation Plans - Option Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding - Number of Shares | shares	3,168,363
Outstanding - beginning of year, Weighted Average Exercise Price | $ / shares	$ 33.57
Granted, Number of Shares | shares	491,615
Granted, Weighted Average-exercise Price | $ / shares	$ 41.56
Exercised, Number of Shares | shares	(297,765)
Exercised, Weighted-average Exercise Price | $ / shares	$ 22.35
Canceled or expired, Number of Shares | shares	(82,345)
Canceled or expired, Weighted-average Exercise Price | $ / shares	$ 40.95
Outstanding - Number of Shares | shares	3,279,868
Outstanding - end of year, Weighted Average Exercise Price | $ / shares	$ 35.60
Outstanding - end of year, Weighted-average Remaining Contractual Term	6 years
Outstanding - end of year, Aggregate Intrinsic Value | $	$ 5.9
Option expected to vest, Number of Shares | shares	3,257,113
Option expected to vest, Weighted-average Exercise Price | $ / shares	$ 35.55
Option expected to vest, Weighted-average Remaining Contractual Term	6 years
Option expected to vest, Aggregate Intrinsic Value | $	$ 5.9
Options exercisable, Number of Shares | shares	2,034,395
Options exercisable, Weighted-average Exercise Price | $ / shares	$ 32.41
Options exercisable, Weighted-average Remaining Contractual Term, Exercisable	5 years
Options exercisable, Aggregate Intrinsic Value | $	$ 5.9