Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Examination
Federal income taxes receivable	$ 12,700
State and Local income taxes receivable	400
Federal, State and Local income taxes receivable		$ 8,100
State income taxes payable		400
Excess tax benefits on stock-based compensation	7,983	9,028	$ 3,914
Remaining available pool of excess tax benefits from prior stock option exercises	31,500
Accrued interest and penalties related to taxes	200	200	200
Unrecognized tax benefits, net of federal income tax benefits	$ 2,900	$ 2,700	$ 1,200
Indiana
Income Tax Examination
Percentage of operating located in Indiana	80.00%