Share Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Share Based Compensation Tables [Abstract]

Valuation and Expense Information

Valuation and Expense Information
		Year Ended December 31,
		2015		2014		2013
Total cost of share-based payment plans	$	6,137	$	8,640	$	13,957
Amounts capitalized in oil and gas properties and equipment	$	2,009	$	3,173	$	4,190
Amounts charged against income, before
income tax benefit	$	4,128	$	5,467	$	9,767
Amount of related income tax benefit recognized
in income before valuation allowances	$	1,645	$	2,285	$	4,083

Securities Authorized for Issuance Under Equity Compensation Plans

			Number of Securities
			Remaining Available
	Number of		for Future Issuance
	Securities to	Weighted	Under Equity
	be Issued	Average	Compensation Plans
	Upon Exercise of	Exercise Price of	(Excluding Securities
	Outstanding	Outstanding	Reflected in the
Plan Category	Options	Options	First Column)
Equity compensation plans approved by	(000's)		(000's)
security holders	519	$58.98	4,555
Equity compensation plans not approved
by security holders	n/a	n/a	n/a
Total	519	$58.98	4,555

Changes in Stock Options Outstanding

		Weighted
		Average
	Number of	Exercise Price
	Options	(US$)
	(000's)
Balance, December 31, 2012	1,357	$16.97	to	$98.87
Forfeited	(110)	$25.68	to	$75.18
Exercised	(1)	$16.97	to	$16.97
Balance, December 31, 2013	1,246	$16.97	to	$98.87
Forfeited	(513)	$33.57	to	$75.18
Exercised	(43)	$16.97	to	$25.68
Balance, December 31, 2014	690	$25.68	to	$98.87
Forfeited	(171)	$25.68	to	$75.18
Balance, December 31, 2015	519	$49.05	to	$98.87

Share Based Compensation by Exercise Price Table

The following table summarizes information about the stock options outstanding and exercisable at December 31, 2015:
					Options Outstanding and Exercisable
						Weighted	Weighted
						Average	Average	Aggregate
					Number	Remaining	Exercise	Intrinsic
Range of Exercise Price					Outstanding	Contractual Life	Price	Value
					(000's)	(Years)
$	50.15	-	$	63.05	103	0.60	$55.37	$-
$	49.05	-	$	62.23	268	1.29	$53.96	$-
$	51.60	-	$	98.87	148	2.45	$70.61	$-

Weighted Average Grant Date Fair Value of Stock Options

		2015		2014		2013
Options forfeited during the year	$	28.00	$	24.40	$	25.44

Valuation Assumptions

Valuation Assumptions
The Company estimates the fair value of the market condition related to the LTIP awards on the date of grant using a Monte Carlo simulation with the following assumptions:
	2015 LTIP	2014 LTIP	2013 LTIP
Volatility of common stock	40.1%	39.0%	39.2%
Average volatility of peer companies	46.5%	n/a	n/a
Average correlation coefficient of peer companies	0.454	n/a	n/a
Risk-free interest rate	1.02%	0.66%	0.40%