Description of Business and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2014

Estimated Useful Lives of Property and Equipment

The estimated useful lives, in years, are shown below:

		Useful Lives
Drilling rigs and other equipment		1.25-15
Buildings		15-20
Other		3-12

Calculation of Basic and Diluted Net Income per Share

The following table presents information necessary to calculate income from continuing operations per share and net income per share for the years ended December 31, 2014, 2013 and 2012, as well as potentially dilutive securities excluded from the weighted average number of diluted common shares outstanding because their inclusion would have been anti-dilutive (in thousands, except per share amounts):

	2014			2013			2012
BASIC EPS:
Net income	$	162,664		$	188,009		$	299,477
Adjust for income attributed to holders of non-vested restricted stock		(1,663	)		(1,859	)		(2,532	)
Income attributed to common stockholders	$	161,001		$	186,150		$	296,945

Weighted average number of common shares outstanding, excluding non-vested shares of restricted stock		144,066			144,356			151,144

Basic net income per common share	$	1.12		$	1.29		$	1.96

DILUTED EPS:
Income attributed to common stockholders	$	161,001		$	186,150		$	296,945

Weighted average number of common shares outstanding, excluding non-vested shares of restricted stock		144,066			144,356			151,144
Add dilutive effect of potential common shares		1,310			947			555
Weighted average number of diluted common shares outstanding		145,376			145,303			151,699

Diluted income per common share	$	1.11		$	1.28		$	1.96

Potentially dilutive securities excluded as anti-dilutive		1,088			2,447			5,416