Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Examination [Line Items]
Federal income taxes receivable	$ 1,300,000	$ 3,700,000
State income taxes payable	800,000
Excess tax benefits on stock-based compensation	3,914,000	1,534,000	270,000
Remaining available pool of excess tax benefits from prior stock option exercises	15,300,000
Accrued interest and penalties related to taxes	200,000	200,000	400,000
Unrecognized tax benefits, net of federal income tax benefits	$ 1,200,000	$ 1,000,000	$ 1,200,000
Indiana
Income Tax Examination [Line Items]
Percentage of operating located in Indiana	80.00%