Stock-Based Compensation (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 3,007	$ 2,156	$ 1,989
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	2,896
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 2 months 12 days
Excess Tax Benefit from Share-based Compensation, Financing Activities	336	203	199
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 34.59	$ 29.18	$ 27.38
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 44.07	$ 42.49	$ 30.24
Stock Issued During Period, Value, New Issues	(854)	(673)	(546)
Equity Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	296	687	743
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning of Period	$ 10.64	$ 10.41
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 11.67	$ 9.30	$ 7.03
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	426	124	457
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	19,051	12,973	108,677
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	40,540	41,579	36,599
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	702		807
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	34,652	31,418	43,042
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	13,588	0	33,508
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Restricted Stock And Performance Shares Combined [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	2,519	1,706	1,652
Minimum [Member] | Equity Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	$ 8.97	$ 7.81	$ 7.81
Maximum [Member] | Equity Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 9.29	$ 14.77	$ 14.77
Granted to Non-Employee Directors [Member] | Fully-Vested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	488	450	337
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period	3,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	10,182	9,960	12,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 47.94	$ 45.16	$ 28.05
The Omnibus Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	900,000
Share-based Compensation Arrangement by Share-based Payment Award, Description	The Omnibus Plan allows for the issuance of 900,000 shares of common stock through the granting of stock options or stock awards (including performance units convertible into stock) to key employees and directors at no less than 100% of fair market value on the date of the grant. The Omnibus Plan provides for the granting of "nonqualified options" with a duration of not more than ten years from the date of grant.
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights	The Omnibus Plan also provides that, unless otherwise set forth in the option agreement, stock options are exercisable in installments of up to 25% annually beginning one year from the date of grant.
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0
The Omnibus Plan [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	14,000		34,000
Stock Issued During Period, Value, New Issues		454
Stock Issued During Period, Value, Treasury Stock Reissued	$ 454		$ 1,130
The 1998 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Description	The 1998 Plan provided for the award of stock options to key employees and directors to purchase up to 900,000 shares of common stock at no less than 100% of fair market value on the date of the grant. The 1998 Plan authorized the granting of "nonqualified options" and "incentive stock options" with a duration of not more than ten years from the date of grant.
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights	The 1998 Plan also provided that, unless otherwise set forth in the option agreement, stock options are exercisable in installments of up to 25% annually beginning one year from date of grant.
Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Description and Terms	Non-employee directors were automatically awarded fully vested, nonqualified stock options to acquire 5,000 shares of the Company's common stock on each date the outside directors were elected at an annual shareholders' meeting to serve as directors. The 1998 Plan was amended in May 2006 to remove the automatic awarding of stock options to outside directors.
The 1998 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	900,000
The 1998 Plan [Member] | Granted to Non-Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	5,000