Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2012

Stock-Based Compensation

Summary of stock option activity under the plan

	Shares			Weighted- Average Exercise Price		Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2011		1,215,083		$	53.95	$	111.4
Granted		130,670			207.11		—
Exercised		(484,788	)		26.29		79.9
Forfeited		(6,762	)		112.29		—
Outstanding at September 30, 2012		854,203			92.62		110.7
Exercisable at September 30, 2012		558,920			59.52		90.9

Summary of restricted stock activity under the Plan

	Shares			Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2011		112,571		$	100.83
Granted		25,662			201.22
Vested		(37,779	)		95.35
Outstanding at September 30, 2012		100,454			128.54

Summary of stock-based compensation costs and related income tax benefits

	Three months ended September 30,						Nine months ended September 30,
	2012			2011			2012			2011
	(in millions)
Stock-based compensation expense(1)	$	2.9		$	2.6		$	8.0		$	7.3
Income tax benefit		(1.1	)		(1.0	)		(3.0	)		(2.7	)
Stock-based compensation expense, net of income taxes	$	1.8		$	1.6		$	5.0		$	4.6

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In addition to our expense associated with the Plan, TNCLP also recognizes stock-based compensation expense for phantom units provided to non-employee directors of TNGP. The expense resulting from these market based liability awards amounted to $0.2 million and $0.8 million for the three and nine months ended September 30, 2012, respectively. Stock compensation expense reported in our consolidated statements of operations and consolidated statements of cash flows includes this phantom unit expense.