Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2011

Earnings Per Share [Abstract]

Computation of earnings per common share

	Years Ended December 31,
	2011		2010		2009
Numerator:
Net income to common shareholders	$	76,759	$	52,206	$	74,775
Net income allocated to participating securities — basic and diluted		866		320		247
Net income allocated to common shareholders—basic and diluted	$	75,893	$	51,886	$	74,528
Denominator:
Weighted-average common shares—basic		65,590		36,876		32,747
Dilutive potential common shares		480		178		187
Weighted average common shares—diluted		66,070		37,054		32,934
Earnings per common share:
Basic	$	1.16	$	1.41	$	2.28
Diluted	$	1.15	$	1.40	$	2.26