Net Income per Share (Tables)

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Computation of basic and diluted earnings per common share

The following table sets forth the computation of basic and diluted earnings per common share:

	Year Ended December 31,
	2015		2014		2013
	(in thousands, except per share amounts)
Numerator:
Net income	$	317,220	$	225,464	$	176,918
Denominator:
Weighted-average shares outstanding, basic	72,208		72,739		72,593
Effect of dilutive stock awards	218		555		406
Adjusted weighted-average shares outstanding, diluted	72,426		73,294		72,999
Net Income per Share:
Basic earnings per common share	$	4.39	$	3.10	$	2.44
Diluted earnings per common share	$	4.38	$	3.08	$	2.42
Anti-dilutive weighted-average shares	52		29		1