Earnings Per Common Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share

Schedule of computation of basic and diluted earnings per share

	Year Ended December 31,
(Dollars and shares in thousands, except for per share amounts)	2017		2016		2015
Basic earnings per common share:
Net income	$	87,554	$	101,282	$	99,473
Weighted-average basic common shares		29,686		23,998		23,966
Basic earnings per common share	$	2.95	$	4.22	$	4.15
Diluted earnings per share:
Net income	$	87,554	$	101,282	$	99,473
Weighted-average basic common shares		29,686		23,998		23,966
Effect of dilutive securities		236		221		258
Weighted-average dilutive shares		29,922		24,219		24,224
Diluted earnings per common share	$	2.93	$	4.18	$	4.11

Schedule of anti-dilutive securities excluded from computation of diluted earnings per common share

	Year Ended December 31,
(Dollars in thousands)	2017					2016					2015
Number of shares					34,712					69,572					47,865
Range of exercise prices	$	69.48	to	$	91.35	$	61.42	to	$	69.48	$	61.42	to	$	66.32