Common Stock Plans (Tables)

12 Months Ended

Dec. 31, 2013

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 or 2011. A summary of performance share award activity as of December 31, 2013, and transactions during the year ended December 31, 2013 is presented below:

	Stock Incentive Plan
	Shares		Weighted Average Price
Nonvested at December 31, 2012	—		$	—
Granted (two-year vesting period)	86,221		61.14
Granted (three-year vesting period)	82,606		62.96
Forfeited	(8,008	)	60.03
Nonvested at December 31, 2013	160,819		$	62.13

Schedule of stock option activity and transactions

A summary of stock option activity as of December 31, 2013, and transactions during the years ended December 31, 2013, 2012 and 2011 are presented below:

	Stock Incentive Plan
	Shares		Weighted Average Exercise Price
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
Granted	137,762		49.22
Exercised	(590,119	)	40.92
Forfeited	(5,074	)	51.85
Outstanding at December 31, 2013	1,191,044		$	51.06
Exercisable at December 31, 2011	677,753		$	43.72
Exercisable at December 31, 2012	987,733		$	43.75
Exercisable at December 31, 2013	713,445		$	49.80
Remaining reserved for issuance at December 31, 2013	2,921,392		—

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	10/15/2013	1/24/2013		1/25/2012		1/26/2011
Awards granted	3,686	134,076		371,040		293,978
Fair market value of stock option at grant	$30.53	$16.66		$18.79		$19.65
Expected life of award	5.8 years	5.8 years		5.8 years		5.8 years
Risk-free interest rate	1.79%	1.01	%	1.07	%	2.45	%
Annualized volatility rate	40.6%	40.3	%	39.6	%	37.8	%
Dividend yield	0.7%	1.2	%	1.0	%	1.0	%

Schedule of outstanding stock options by range of exercise prices

The following table summarizes options outstanding as of December 31, 2013:

Stock Incentive Plan
Range of Exercise Prices	Shares	Weighted Average Remaining Contractual Life
$46.45	59,330	3.00 years
$60.56	99,965	4.00 years
$29.79	78,222	5.00 years
$46.69	203,469	6.00 years
$54.99	266,166	7.00 years
$54.11	349,754	8.00 years
$48.36	130,452	9.00 years
$80.48	3,686	9.83 years
$29.79-$80.48	1,191,044	6.77 years

Schedule of restricted stock activity and transactions

A summary of restricted stock activity as of December 31, 2013, and transactions during the years ended December 31, 2013, 2012 and 2011 is presented below:

	Stock Incentive Plan
	Shares		Weighted Average Price
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
Granted	52,650		52.34
Forfeited	(1,247	)	48.36
Nonvested at December 31, 2013	62,518		$	51.16

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

A summary of stock appreciation rights activity as of December 31, 2013, and transactions during the years ended December 31, 2013, 2012 and 2011 are presented below:

	Stock Appreciation Rights Plan
	Shares		Weighted Average Exercise Price
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
Granted	88,000		48.36
Exercised/forfeited	(363,653	)	39.66
Outstanding at December 31, 2013	377,377		$	49.48

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, 2013:

Grant date	1/24/2013	1/24/2013	1/26/2011	1/26/2011	1/27/2010
		(modified)		(modified)
Awards granted	87,069	931	182,199	7,785	171,749
Fair market value of award	$34.66	$27.89	$27.07	$24.21	$30.10
Expected life of award	5.6 years	2.5 years	3.6 years	2.5 years	3.0 years
Risk-free interest rate	2.04%	0.56%	1.06%	0.56%	0.80%
Annualized volatility rate	40.6%	40.6%	40.6%	40.6%	40.6%
Dividend yield	0.8%	0.8%	0.8%	0.8%	0.8%

Grant date	2/13-16/2009	1/28/2009	2/4/2008	2/1/2007
Awards granted	3,292	305,257	67,093	85,906
Fair market value of award	$39.87	$41.18	$18.50	$27.03
Expected life of award	2.5 years	2.5 years	2.0 years	1.5 years
Risk-free interest rate	0.58%	0.58%	0.39%	0.23%
Annualized volatility rate	40.6%	40.6%	40.6%	40.6%
Dividend yield	0.8%	0.8%	0.8%	0.8%

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, 2013, and transactions during the years ended December 31, 2013, 2012 and 2011 are presented below:

	Petrotech Incentive Plan
	Shares
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
Granted (three-year vesting period)	92,418
Granted (17 month vesting period)	2,952
Paid	(36,792	)
Forfeited	(26,529	)
Outstanding at December 31, 2013	173,292