Net Income Per Common Share (Tables)

9 Months Ended

Sep. 30, 2012

Net Income Per Common Share [Abstract]

Basic and diluted net income per common share

	Income (Numerator)		Shares (Denominator)		Per Share Amount
	(Dollars in thousands, except per share data)
Three Months Ended September 30, 2012
Basic
Income available to common stockholders	$	13,860		15,174,755	$	0.91
Effect of stock options		—		272,639
Diluted
Income available to common stockholders plus assumed exercises of stock options	$	13,860		15,447,394	$	0.90
Three Months Ended September 30, 2011
Basic
Income available to common stockholders	$	12,553		15,210,090	$	0.82
Effect of stock options		—		261,569
Diluted
Income available to common stockholders plus assumed exercises of stock options	$	12,553		15,471,659	$	0.81
Nine Months Ended September 30, 2012
Basic
Income available to common stockholders	$	39,594		15,155,035	$	2.61
Effect of stock options		—		276,063
Diluted
Income available to common stockholders plus assumed exercises of stock options	$	39,594		15,431,098	$	2.57
Nine Months Ended September 30, 2011
Basic
Income available to common stockholders	$	34,023		15,316,218	$	2.22
Effect of stock options		—		286,905
Diluted
Income available to common stockholders plus assumed exercises of stock options	$	34,023		15,603,123	$	2.18

Average exercise prices of options excluded from the computation of diluted net income per common share

	Shares		Average Exercise Price
Three Months Ended September 30, 2012		479,000	$	39.21
Three Months Ended September 30, 2011		649,347	$	38.61
Nine Months Ended September 30, 2012		597,200	$	38.66
Nine Months Ended September 30, 2011		535,781	$	38.86