Income Taxes (Summary of Tax Expense and Effective Tax Rates) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income before income taxes	$ 2,584	$ 157	$ 48,118	$ 31,854
Income tax expense	$ 955	$ 1,690	$ 13,519	$ 7,704
Effective tax rate (percent)	37.00%	1076.40%	28.10%	24.20%