Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Computation of Earnings Per Common Share

A summary of the information used in the computation of earnings per common share follows:

	Years Ended December 31,
($ in thousands, except per share amounts)	2015		2014		2013
Numerator:
Net income to common shareholders	$	131,461	$	175,722	$	163,356
Net income allocated to participating securities – basic and diluted	$	2,895	$	3,631	$	3,105
Net income allocated to common shareholders – basic and diluted	$	128,566	$	172,091	$	160,251
Denominator:
Weighted-average common shares – basic		78,197		81,804		83,066
Dilutive potential common shares		110		230		101
Weighted average common shares – diluted		78,307		82,034		83,167
Earnings per common share:
Basic	$	1.64	$	2.10	$	1.93
Diluted	$	1.64	$	2.10	$	1.93