Income Tax (tables)

3 Months Ended

Mar. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expenses (Benefit)

	Three Months Ended March 31,
Dollars in thousands	2014			2013
Income tax at statutory rates (federal and state)	$	25,721		$	25,239
Increase (decrease):
Differences required to be flowed-through by regulatory commissions	1,433			1,512
Other, net	(169		)	(791		)
Income tax expense	$	26,985		$	25,960
Effective income tax rate	41.6		%	40.8		%