Stock-Based Compensation (Narrative) (Details) - $ / shares	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period specified in grant, in years							3 years
Granted	5,337	4,874	192,407	6,088	4,594	223,495
2004 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Underlying stock option and restricted stock awards available for grant	0						0
Amended and Restated Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	6,250,000						6,250,000
Maximum number of shares may be issued pursuant to stock awards, stock units and other stock-based awards							3,125,000
Maximum number of shares subject to grants to any one individual in any one year							500,000
Underlying stock option and restricted stock awards available for grant	1,955,579						1,955,579
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, in years							3 years
Granted							152,068
Weighted average fair value of stock awards granted							$ 43.18	$ 55.43
Amortization period of fair value of shares, in months							36 months
Performance Share Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target award amount the grantee may earn							0.00%
Performance Share Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target award amount the grantee may earn							200.00%
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted period							3 years
Granted							85,829
Weighted average fair value of stock awards granted							$ 44.44	$ 49.40
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares							0	0
Vesting period, start, in years							1 year
Vesting period, in years							10 years
Stock Options [Member] | Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							33.00%
Stock Options [Member] | Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							33.00%
Stock Options [Member] | Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							33.00%
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted							1,068
Weighted average fair value of stock awards granted							$ 46.83	$ 34.02
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted							11,487
Weighted average fair value of stock awards granted							$ 45.71	$ 40.54