Shareholders' Equity and Stock Compensation (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
Stock repurchased during period (in shares)	225,000
Stock repurchased during period	$ 3,900,000
Shareholders Equity and Share-Based Payments [Line Items]
Share-based Compensation, Excluding Accelerated Compensation Cost		$ 2,200,000	$ 2,000,000	$ 5,900,000	$ 6,700,000
Total income tax benefit recognized related to stock-based compensation		834,000	774,000	2,300,000	2,600,000
Proceeds from stock options exercised				548,000	1,098,000
Income tax benefits received		126,000	185,000	2,500,000	5,400,000
Employee Stock Option
Shareholders Equity and Share-Based Payments [Line Items]
Total intrinsic value of options exercised		52,000	81,000	193,000	259,000
Proceeds from stock options exercised		85,000	322,000	548,000	1,100,000
Cash from stock options exercised		85,000	365,000	354,000	432,000
Total unrecognized compensation cost related to nonvested stock awards		3,000		$ 3,000
Expected recognized over a weighted-average period, years				2 months 16 days
Restricted Stock
Shareholders Equity and Share-Based Payments [Line Items]
Total fair value of restricted stock shares/units vested and released		193,000	331,000	$ 5,400,000	11,600,000
Total unrecognized compensation cost related to nonvested stock awards		10,700,000		$ 10,700,000
Expected recognized over a weighted-average period, years				1 year 6 months 15 days
Restricted Stock Units (RSUs)
Shareholders Equity and Share-Based Payments [Line Items]
Total fair value of restricted stock shares/units vested and released		80,000	$ 65,000	$ 891,000	$ 2,200,000
Total unrecognized compensation cost related to nonvested stock awards		$ 504,000		$ 504,000
Expected recognized over a weighted-average period, years				5 months 27 days