Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Change in Accounting Estimate [Line Items]
Income tax expense	$ 4,467	$ 1,216
Effective tax rate	31.30%	14.60%
Expected effective income tax rate for the year	34.00%
Statutory federal tax rate	35.00%
Investment Tax Credit Carryforward [Member]
Change in Accounting Estimate [Line Items]
Income tax expense	$ (700)