Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

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

Summary of Stock-Based Compensation Expense

Stock-based compensation expense is summarized as follows:

	Years Ended December 31,
	2015		2014		2013
($ in thousands)
Stock-based compensation expense	$	11,863	$	9,778	$	7,960

Summary of Restricted Stock Units Activity

RSU activity for the year ended December 31, 2015 is summarized as follows:

	Number of shares		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2014	179,936		$	143.25
Granted	118,380		$	134.37
Forfeited	(19,289	)	$	142.41
Settled	(87,410	)	$	102.00
Outstanding at December 31, 2015	191,617		$	156.66

Summary of Stock Option Activity

Stock option activity for the year ended December 31, 2015 is summarized as follows:

	Number of shares		Weighted Average Exercise Price
Outstanding at December 31, 2014	162,824		$	18.79
Granted	—		$	—
Exercised	(6,188	)	$	19.04
Forfeited	—		$	—
Outstanding at December 31, 2015	156,636		$	18.78
Vested and exercisable at December 31, 2015	156,636		$	18.78