Stock Options and Incentive Plans (Schedules of Executive Management Share-based Compensation Activity) (Details) (Performance Shares [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Performance Shares [Member]
Number of shares
Shares/Share units potentially payable, beginning balance	229,361	161,280	90,871
Forfeitures
Payments	(118,364)	(44,347)	(34,268)
Shares accrued	74,567	112,428	104,677
Shares/Share units potentially payable, ending balance	185,564	229,361	161,280
Weighted average grant date value per share
Shares/Share units potentially payable, beginning balance	$ 24.13	$ 23.74	$ 22.40
Forfeitures
Payments	$ 23.05	$ 24.62	$ 22.40
Shares accrued	$ 31.62	$ 27.15	$ 24.62
Shares/Share units potentially payable, ending balance	$ 27.51	$ 24.13	$ 23.74
Year-end intrinsic value
Shares potentially payable	$ 5,202	$ 3,729	$ 2,153
Shares potentially payable	$ 6,667	$ 5,202	$ 3,729

Stock Options and Incentive Plans (Schedules of Executive Management Share-based Compensation Activity) (Details) (Performance Shares [Member], USD $)
In Thousands, except Share data, unless otherwise specified

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Performance Shares [Member]

Number of shares

Shares/Share units potentially payable, beginning balance

229,361

161,280

90,871

Forfeitures

Payments

(118,364)

(44,347)

(34,268)

Shares accrued

74,567

112,428

104,677

Shares/Share units potentially payable, ending balance

185,564

229,361

161,280

Weighted average grant date value per share

Shares/Share units potentially payable, beginning balance

$ 24.13

$ 23.74

$ 22.40

Forfeitures

Payments

$ 23.05

$ 24.62

$ 22.40

Shares accrued

$ 31.62

$ 27.15

$ 24.62

Shares/Share units potentially payable, ending balance

$ 27.51

$ 24.13

$ 23.74

Year-end intrinsic value

Shares potentially payable

$ 5,202

$ 3,729

$ 2,153

Shares potentially payable

$ 6,667

$ 5,202

$ 3,729

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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