Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Stock-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options	$ 1,600
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	4,359	$ 2,420	$ 2,102
Allocated Share-based Compensation Expense	$ 7,891	$ 6,914	$ 6,007
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	3 years
Shares granted during the year	58,610	58,302	62,075
Shares vested during the year	(52,385)	(60,379)	(52,899)
Unvested shares at end of year	109,806	106,091	112,042
Unrecognized compensation expense at end of year (in thousands)	$ 1,853	$ 1,705	$ 1,349
Total Shareholder Return Market-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year	116,435	116,435	117,550
Shares vested during the year	(111,665)	(171,334)	(167,584)
TSR shares earned based on market metrics	132,887	222,734	97,199
Unvested shares at end of year	222,228	223,697	287,834
Unrecognized compensation expense at end of year (in thousands)	$ 3,409	$ 3,219	$ 2,833
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year	57,521	58,259	59,025
Shares vested during the year	(55,835)	0	0
TSR shares earned based on market metrics	90,460	0	0
Unvested shares at end of year	110,452	111,887	58,017
Unrecognized compensation expense at end of year (in thousands)	$ 1,671	$ 1,840	$ 1,577
Total Shareholder Return Market-Based Awards and Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	3 years
Allocated Share-based Compensation Expense	$ 1,500	$ 1,500
Minimum [Member] | Total Shareholder Return Market-Based Awards and Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued range, percent of the performance shares granted	0.00%
Maximum [Member] | Total Shareholder Return Market-Based Awards and Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued range, percent of the performance shares granted	200.00%