Stock-Based Compensation Plans (Summary Of Restricted Stock Activity) (Detail) (USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Options outstanding, at end of period, Weighted-Average Exercise Price (in dolars per share)	$ 29.47	$ 29.47
Time Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Restricted stock, at beginning of period, Number of Shares	409,691	384,385
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dolars per share)	$ 21.36	$ 20.20
Granted, Number of Shares	2,819	186,898
Granted, Weighted-average Grant Date Fair Value (in dolars per share)	$ 20.52	$ 22.39
Vested, Number of Shares	69,413	219,353
Vested, Weighted-average Grant Date Fair Value (in dolars per share)	$ 19.70	$ 19.61
Forfetied/Modified Number of Shares	57,044	65,877
Forfeited/Modified Weighted-average Grant Date Fair Value (in dollars per share)	$ 21.24	$ 21.30
Restricted stock, at end of period, Number of Shares	286,053	286,053
Options outstanding, at end of period, Weighted-Average Exercise Price (in dolars per share)	$ 21.78	$ 21.78
Performance-Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Restricted stock, at beginning of period, Number of Shares	129,277	0
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dolars per share)	$ 25.44	$ 0
Granted, Number of Shares	0	149,479
Granted, Weighted-average Grant Date Fair Value (in dolars per share)		$ 25.44
Vested, Number of Shares	11,897	32,099
Vested, Weighted-average Grant Date Fair Value (in dolars per share)	$ 25.44	$ 25.44
Forfetied/Modified Number of Shares	6,338	6,338
Forfeited/Modified Weighted-average Grant Date Fair Value (in dollars per share)	$ 25.44	$ 25.44
Restricted stock, at end of period, Number of Shares	111,042	111,042
Options outstanding, at end of period, Weighted-Average Exercise Price (in dolars per share)	$ 25.44	$ 25.44
Time Based Restricted Stock Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Restricted stock, at beginning of period, Number of Shares	0
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dolars per share)	$ 0.00	$ 0.00
Forfeited, Number of Shares	51,496
Forfeited, Weighted-average Grant Date Fair Value (in dolars per share)	$ 21.11	$ 21.11
Vested, Number of Shares	9,215
Vested, Weighted-average Grant Date Fair Value (in dolars per share)	$ 18.22	$ 18.22
Restricted stock, at end of period, Number of Shares	42,281	42,281
Options outstanding, at end of period, Weighted-Average Exercise Price (in dolars per share)	$ 21.74	$ 21.74

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

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- Definition

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.

+ References

+ Details

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- Definition

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).

+ References

+ Details

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- Definition

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(a)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(a)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

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

+ References

+ Details

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Modified in Period

+ References

No definition available.

+ Details

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Modified, Weighted Average Grant Date Fair Value

+ References

No definition available.

+ Details

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