Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Schedule of reconciliation of the numerators and denominators used in the basic and diluted per-share computations

A reconciliation of the numerators and denominators used in the basic and diluted per-share computations is presented as follows for each class of common stock: 

	Three months ended March 31,
	2018					2017
(dollars in thousands, except per share data)	Allocated net income (numerator)		Weighted shares (denominator)	Per-share amount		Allocated net income (numerator)		Weighted shares (denominator)	Per-share amount
Class A – Basic EPS:
Income available to Class A stockholders	$	65,220	46,187,908	$	1.41	$	47,484	46,188,522	$	1.03
Dilutive effect of stock-based awards	0		21,920	—		0		119,238	—
Assumed conversion of Class B shares	538		6,100,800	—		392		6,100,800	—
Class A – Diluted EPS:
Income available to Class A stockholders on Class A equivalent shares	$	65,758	52,310,628	$	1.26	$	47,876	52,408,560	$	0.91
Class B – Basic and diluted EPS:
Income available to Class B stockholders	$	538	2,542	$	212	$	392	2,542	$	154