Income Tax (tables)

3 Months Ended

Mar. 31, 2015

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expenses (Benefit)

	Three Months Ended March 31,
Dollars in thousands	2015			2014
Income tax at statutory rates (federal and state)	$	18,892		$	25,721
Increase (decrease):
Differences required to be flowed-through by regulatory commissions	1,329			1,433
Other, net	(1,138		)	(169		)
Income tax expense	$	19,083		$	26,985
Effective income tax rate	40.1		%	41.6		%