Common Stock Plans (Tables)

12 Months Ended

Dec. 31, 2012

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of performance share award activity

No performance share awards were granted in 2012, 2011 or 2010. A summary of performance share award activity is presented below:

	Stock Incentive Plan
	Shares		Weighted Average Price
Nonvested at December 31, 2009	111,143		$	43.81
Vested and paid	(111,143	)	43.81
Nonvested at December 31, 2010	—		$	—

Schedule of stock option activity and transactions

A summary of stock option activity as of December 31, 2012, and transactions during the years ended December 31, 2012, 2011 and 2010 are presented below:

	Stock Incentive Plan
	Shares		Weighted Average Exercise Price
Outstanding at December 31, 2009	1,107,809		$	36.83
Granted	281,110		46.69
Exercised	(111,676	)	23.83
Forfeited	(1,200	)	13.72
Outstanding at December 31, 2010	1,276,043		40.16
Granted	293,978		54.99
Exercised	(227,405	)	32.33
Forfeited	(4,375	)	35.35
Outstanding at December 31, 2011	1,338,241		44.77
Granted	371,040		54.11
Exercised	(58,471	)	24.55
Forfeited	(2,335	)	46.45
Outstanding at December 31, 2012	1,648,475		$	47.58
Exercisable at December 31, 2010	574,992		$	41.16
Exercisable at December 31, 2011	677,753		$	43.72
Exercisable at December 31, 2012	987,733		$	43.75
Remaining reserved for issuance at December 31, 2012	3,418,881		—

Schedule of stock options valuation assumptions

The Company uses the Black-Scholes pricing model to calculate the fair values of the options awarded. For purposes of this valuation the following assumptions were used to derive the fair values:

Grant date	1/25/2012		1/26/2011		1/27/2010
Awards granted	371,040		293,978		281,110
Fair market value of stock option at grant	$18.79		$19.65		$16.47
Expected life of award	5.8 years		5.8 years		5.7 years
Risk-free interest rate	1.07	%	2.45	%	2.76	%
Annualized volatility rate	39.6	%	37.8	%	37.3	%
Dividend yield	1.0	%	1.0	%	1.1	%

Schedule of outstanding stock options by range of exercise prices

The following table summarizes options outstanding as of December 31, 2012:

Stock Incentive Plan
Range of Exercise Prices	Shares	Weighted Average Remaining Contractual Life
$14.86	16,270	.08 years
$21.38	5,560	1.08 years
$46.45	150,710	4.00 years
$55.08	7,260	4.50 years
$60.56	184,565	5.00 years
$29.79	333,232	6.00 years
$43.30	4,750	6.67 years
$46.69	281,110	7.00 years
$54.99	293,978	8.00 years
$54.11	371,040	9.00 years
$14.86-$60.56	1,648,475	6.83 years

Schedule of restricted stock activity and transactions

A summary of restricted stock activity as of December 31, 2012, and transactions during the years ended December 31, 2012, 2011 and 2010 is presented below:

	Stock Incentive Plan
	Shares		Weighted Average Price
Nonvested at December 31, 2009	53,005		$	32.66
Vested	(28,855	)	30.30
Nonvested at December 31, 2010	24,150		35.49
Vested	(14,875	)	30.81
Nonvested at December 31, 2011	9,275		42.99
Granted	11,115		45.24
Vested	(9,275	)	42.97
Nonvested at December 31, 2012	11,115		$	45.24

Schedule of Share-based Compensation, Stock Appreciation Rights Award Activity [Table Text Block]

A summary of stock appreciation rights activity as of December 31, 2012, and transactions during the years ended December 31, 2012, 2011 and 2010 are presented below:

	2004 Stock Appreciation Rights Plan
	Shares		Weighted Average Exercise Price
Outstanding at December 31, 2009	503,215		$	35.46
Granted	171,749		46.69
Exercised/forfeited	(18,624	)	37.65
Outstanding at December 31, 2010	656,340		38.30
Granted	189,984		54.99
Exercised/forfeited	(69,106	)	41.21
Outstanding at December 31, 2011	777,218		42.00
Exercised/forfeited	(124,188	)	30.90
Outstanding at December 31, 2012	653,030		$	44.14

Schedule of stock appreciation rights valuation assumptions

For purposes of this valuation the following assumptions were used to derive the fair values as of December 31, 2012:

Grant date	1/26/2011	1/27/2010	2/13-16/2009	1/28/2009	2/4/2008	2/1/2007
Awards granted	189,984	171,749	3,292	305,257	67,093	85,906
Fair market value of award	$11.19	$11.93	$17.57	$18.46	$5.80	$9.25
Expected life of award	4.6 years	3.6 years	3.0 years	3.0 years	2.6 years	2.0 years
Risk-free interest rate	0.63%	0.44%	0.37%	0.37%	0.31%	0.26%
Annualized volatility rate	40.4%	40.4%	40.4%	40.4%	40.4%	40.4%
Dividend yield	1.2%	1.2%	1.2%	1.2%	1.2%	1.2%

Petrotech Incentive Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of incentive units activity

A summary of Petrotech unit activity as of December 31, 2012, and transactions during the years ended December 31, 2012, 2011 and 2010 are presented below:

	Petrotech Incentive Plan
	Shares
Outstanding at December 31, 2009	32,350
Granted (three-year vesting period)	2,442
Paid	(26,587	)
Outstanding at December 31, 2010	8,205
Granted (three-year vesting period)	6,314
Paid	(1,914	)
Forfeited	(1,544	)
Outstanding at December 31, 2011	11,061
Granted (three-year vesting period)	102,349
Granted (two-year vesting period)	3,768
Granted (18 month vesting period)	40,822
Paid	(3,281	)
Forfeited	(13,476	)
Outstanding at December 31, 2012	141,243