Stock Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock compensation expense and related net tax benefit

The following table presents a summary of the total share-based compensation expense and the related net tax benefit associated with the Company’s various employee share-based compensation plans for the years ended December 31, 2017, 2016 and 2015:

($ in thousands)	Year Ended December 31,
	2017		2016		2015
Stock compensation costs	$	24,657	$	22,102	$	16,502
Related net tax benefits for stock compensation plans	$	4,775	$	1,055	$	3,291

Summary of activity for time-based and performance-based restricted stock units

The following table presents a summary of the activity for the Company’s time-based and performance-based RSUs for the year ended December 31, 2017 based on the target amount of awards:

	2017
	Time-Based RSUs				Performance-Based RSUs
	Shares		Weighted- Average Grant Date Fair Value		Shares		Weighted- Average Grant Date Fair Value
Outstanding at beginning of year	1,218,714		$	35.92	410,746		$	35.27
Granted	411,290		55.28		131,597		56.59
Vested	(312,226	)	36.55		(118,044	)	36.85
Forfeited	(151,198	)	40.38		—		—
Outstanding at end of year	1,166,580		$	42.00	424,299		$	41.44

Schedule of information related to stock options

The following table presents information related to stock options for the years ended December 31, 2017, 2016 and 2015:

($ in thousands)	Year Ended December 31,
	2017		2016		2015
Cash proceeds from options exercised	$	—	$	—	$	874
Net tax benefit recognized from options exercised	$	—	$	—	$	320
Total intrinsic value of options exercised	$	—	$	—	$	760