Stock Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended		9 Months Ended	3 Months Ended		9 Months Ended	0 Months Ended	3 Months Ended		9 Months Ended	0 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Jun. 30, 2014 Stock options Stock Compensation Plan	Mar. 31, 2014 Stock options Stock Compensation Plan	Sep. 30, 2014 Stock options Stock Compensation Plan	Jun. 30, 2014 Restricted Stock Units (RSUs) Stock Compensation Plan 2 year vesting period	Jan. 31, 2013 Restricted Stock Units (RSUs) Stock Compensation Plan Vesting Period, Three [Member]	Jun. 30, 2014 Restricted Stock Units (RSUs) Stock Compensation Plan Vesting Period, Three [Member]	Sep. 30, 2014 Restricted Stock Units (RSUs) Stock Compensation Plan Vesting Period, Three [Member]	Sep. 30, 2014 Restricted Stock Units (RSUs) Petrotech Incentive Plan	Jun. 30, 2014 Performance share awards Stock Compensation Plan 2 year vesting period	Mar. 31, 2014 Performance share awards Stock Compensation Plan 2 year vesting period	Sep. 30, 2014 Performance share awards Stock Compensation Plan 2 year vesting period	Jun. 30, 2014 Performance share awards Stock Compensation Plan Vesting Period, Three [Member]	Mar. 31, 2014 Performance share awards Stock Compensation Plan Vesting Period, Three [Member]	Sep. 30, 2014 Performance share awards Stock Compensation Plan Vesting Period, Three [Member]	Sep. 30, 2014 Performance share awards Petrotech Incentive Plan	Mar. 31, 2014 Performance share awards Petrotech Incentive Plan	Mar. 31, 2014 Performance share awards Petrotech Incentive Plan Vesting Period, Three [Member]	Sep. 30, 2014 Performance share awards Petrotech Incentive Plan Vesting Period, Three [Member]	Sep. 30, 2014 Performance share awards Petrotech Incentive Plan 20 months vesting period	Sep. 30, 2014 Performance share awards Petrotech Incentive Plan 20 months vesting period	Sep. 30, 2014 Stock Appreciation Rights (SARs)	Mar. 31, 2014 Stock Appreciation Rights (SARs)	Sep. 30, 2014 Stock Appreciation Rights (SARs)	Sep. 30, 2014 Deferred Compensation	Sep. 30, 2014 Deferred Compensation
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period			3 years	2 years			3 years				2 years			3 years				3 years		20 months			3 years
Expiration period			10 years
Grants in period, options	2,439	107,868		6,312
Grants in period, options, fair value	$ 32.22	$ 27.57
Grants in period (in shares)					41,664	928		36,920	650	287		1,467	63,842			28,840	9,728		596			62,749
Grant date fair value				$ 78.99		$ 79.15
Grants in period, fair value (in dollars per share)					$ 70.68			$ 94.38	$ 137.11	$ 118.99		$ 109.02	$ 93.13		$ 72.06				$ 72.14		$ 28.71
Noncash payments for repurchase of common stock																								$ 36	$ 400