Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2012

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Allocation of Share-based Compensation Costs by Plan

The following table summarizes our stock-based compensation expense for the years ended December 31:

($ in millions)	2012		2011		2010
Stock option and appreciation rights	$	5.3	$	4.4	$	3.7
Performance-vesting shares	6.0		3.0		2.2
Performance-vesting units	0.9		0.2		0.1
Performance-vesting shares/units dividend equivalents	0.1		0.1		0.2
Employee stock purchase plan	0.4		0.3		0.3
Deferred compensation plans	2.8		0.4		1.3
Total stock-based compensation expense	$	15.5	$	8.4	$	7.8

Schedule of Stock Options Activity

The following table summarizes changes in outstanding options:

(in millions, except per share data)	2012			2011			2010
Options outstanding, January 1	2.9			2.9			2.7
Granted	0.6			0.5			0.6
Exercised	(0.7		)	(0.4		)	(0.3		)
Forfeited	—			(0.1		)	(0.1		)
Options outstanding, December 31	2.8			2.9			2.9
Options exercisable, December 31	1.5			1.8			1.8
Weighted Average Exercise Price	2012			2011			2010
Options outstanding, January 1	$	35.76		$	32.32		$	29.09
Granted	42.94			40.85			42.47
Exercised	26.23			17.69			14.88
Forfeited	40.75			39.69			41.47
Options outstanding, December 31	$	39.67		$	35.76		$	32.32
Options exercisable, December 31	$	38.02		$	32.91		$	27.77

Schedule of Stock Appreciation Rights Award Activity

The following table summarizes changes in outstanding SARs:

	2012		2011		2010
SARs outstanding, January 1	160,168		111,048		78,512
Granted	72,509		63,024		36,255
Exercised	(37,834	)	(7,685	)	(3,719	)
Forfeited	—		(6,219	)	—
SARs outstanding, December 31	194,843		160,168		111,048
SARs exercisable, December 31	55,146		58,900		41,439

Weighted Average Exercise Price	2012		2011		2010
SARs outstanding, January 1	$	40.34	$	39.74	$	38.04
Granted	42.44		41.13		42.68
Exercised	37.81		39.15		32.50
Forfeited	—		39.18		—
SARs outstanding, December 31	41.61		40.34		39.74
SARs exercisable, December 31	$	41.40	$	39.72	$	39.16

Schedule of Nonvested Performance-based Share Activity

The following table summarizes changes in our outstanding PVS awards:

	2012			2011			2010
Non-vested PVS awards, January 1	328,519			347,550			327,498
Granted at target level	104,840			101,099			123,068
Adjustments above/(below) target	(60,077		)	(58,175		)	(48,364		)
Vested and converted	(41,930		)	(51,756		)	(50,337		)
Forfeited	(5,021		)	(10,199		)	(4,315		)
Non-vested PVS awards, December 31	326,331			328,519			347,550
Weighted Average Grant Date Fair Value	2012			2011			2010
Non-vested PVS awards, January 1	$	38.77		$	39.21		$	39.63
Granted at target level	42.66			40.85			42.34
Adjustments above/(below) target	31.28			41.95			44.99
Vested and converted	42.44			40.85			38.22
Forfeited	41.95			38.46			37.61
Non-vested PVS awards, December 31	$	42.17		$	38.77		$	39.21

Schedule of Nonvested Performance-based Units Activity

The following table summarizes changes in our outstanding PVU awards:

	2012			2011			2010
Non-vested PVU awards, January 1	27,286			23,420			20,792
Granted at target level	13,550			13,442			7,697
Adjustments above/(below) target	(3,578		)	(4,165		)	(2,484		)
Vested and converted	(2,638		)	(3,963		)	(2,585		)
Forfeited	—			(1,718		)	—
Non-vested PVU awards, December 31	34,620			27,286			23,420
Weighted Average Grant Date Fair Value	2012			2011			2010
Non-vested PVU awards, January 1	$	39.30		$	38.94		$	39.17
Granted at target level	42.44			41.11			42.30
Adjustments above/(below) target	30.01			41.05			38.22
Vested and converted	42.44			40.85			38.22
Forfeited	—			37.55			—
Non-vested PVU awards, December 31	$	42.01		$	39.30		$	38.94