Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	12 Months Ended
	May 05, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards		$ 11.3
Unrecognized compensation cost, expect to be capitalized		2.1
Weighted average years over which this cost will be recognized		0 years 9 months 18 days
Maximum number of shares of common stock allowed for the issuance		3,300,000
Number of Shares, Beginning Balance							614,133
Performance Evaluation Period		3 years
Number of Directors receiving options	8
Contingent options	3,063
Options granted	24,504
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Performance Based Shares to be Received Based On Second Year Results		100.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding		118,030	138,980	184,765		219,625
Expire years		10 years
Shares vested		0	0	6,200
Weighted average remaining contractual term, years		1 year 8 months 12 days
Grant date fair value				0.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		(18,850)	(42,285)	(32,360)
Exercised intrinsic value		0.4
Maximum Number of Shares of Common Stock Previously Allowed for the Issuance		2,700,000
Vesting rate of options		20.00%
Cash received from the options exercised		0.1
Weighted Average Grant Date Price, Ending Balance		$ 33.03	$ 31.39	$ 31.11		$ 29.61
Exercisable options intrinsic value		1.4
Options granted		0	0	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		376,445	211,050	450,355
Number of Shares, Beginning Balance		447,961	446,125	507,071			589,527
Aggregate intrinsic value		27.7
Restricted stock awards to be vested		30.00%
Restricted stock awards granted to designated executive officers		46,441	20,062
Grant date fair value		16.9	10.8	16.9
Number of Shares, Vested		(220,788)	(190,262)	(496,497)
Exercised intrinsic value		10.0
Restricted stock weighted average remaining contractual term, years		1 year 1 month 6 days
Weighted Average Grant Date Price, Ending Balance		$ 48.11	$ 47.44	$ 47.39		$ 47.46
Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards vested period		2 years
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards vested period		3 years
Restricted Stock [Member] | First Half Of 2014 [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance percentage criteria		50.00%
Restricted Stock [Member] | First Half Of 2014 [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance percentage criteria		150.00%
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		0	0	0
Expire years		10 years
Shares vested		0	33,745	48,632
Number of Shares, Beginning Balance		145,901	145,901	145,901			145,901
Aggregate intrinsic value		0.1
Weighted average remaining contractual term, years		4 years 7 months 6 days
Number of Shares, Vested		0	0	0
Weighted Average Grant Date Price, Ending Balance		$ 46.59	$ 46.59	$ 46.59		$ 46.59
Directors Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		0	31,500	52,504		437
Number of Shares, Beginning Balance		199,500	178,500	143,496			192,500
Aggregate intrinsic value		0.9
Weighted average remaining contractual term, years		5 years 3 months 18 days
Director option awards			3,500
Restricted stock awards vested period		0 years 6 months
Grant date fair value			0.7	0.8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		(7,000)	(10,500)	(3,500)
Cash received from the options exercised		0.1
Weighted Average Grant Date Price, Ending Balance		$ 49.39	$ 48.37	$ 48.77		$ 49.38
Exercisable options intrinsic value		$ 0.2
Contingent options	3,063
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares of common stock allowed for the issuance		2,000,000					2,000,000
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted			31,500	52,504	[1]

[1] On May 29, 2009, eight of our directors were each issued 3,063 options contingent on shareholder approval, which was received at the May 5, 2010 annual shareholders’ meeting. These 24,504 options granted and vested simultaneously with that approval.