Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

Stock-based Compensation [Abstract]

Compensation Cost and Related Tax Benefits

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(in millions)	2014		2013		2014		2013
Stock-based compensation expense	$	3.8	$	2.1	$	7.3	$	5.7
Tax benefit		(1.4)		(0.7)		(2.6)		(2.0)
Stock-based compensation expense, net of taxes	$	2.4	$	1.4	$	4.7	$	3.7

Summary of Stock Option Plan Activity

	Six Months Ended June 30,
	2014			2013
(in whole shares and dollars)	Shares		Weighted Average Exercise Price	Shares		Weighted Average Exercise Price
Outstanding, beginning of period	2,049,173	$	41.18	2,892,882	$	38.28
Granted	683,200		58.02	537,300		42.51
Exercised	(243,491)		38.66	(798,790)		32.84
Forfeited or cancelled	(34,085)		41.84	(164,500)		41.74
Outstanding, end of period	2,454,797		46.10	2,466,892		40.74

Summary of Restricted Stock Activity

	Six Months Ended June 30,
	2014			2013
(in whole shares and dollars)	Shares		Weighted Average Grant Date Fair Value	Shares		Weighted Average Grant Date Fair Value
Time-based restricted stock units:
Outstanding, beginning of period	525,980	$	41.20	750,837	$	40.15
Granted	94,240		58.02	130,912		42.80
Vested	(202,006)		42.09	(259,440)		39.60
Forfeited	(9,300)		40.73	(37,257)		40.49
Outstanding, end of period	408,914		44.65	585,052		40.96
Performance-based and market-based restricted stock units:
Outstanding, beginning of period	184,626	$	40.42	132,775	$	39.97
Granted	60,338		55.73	79,850		41.67
Vested	(22,826)		44.78	-		-
Forfeited	(3,800)		37.90	(22,700)		40.83
Outstanding, end of period	218,338		44.24	189,925		40.58