Stock-Based Compensation, Dividend Restrictions, and Calculations of Earnings Per Share of Common Stock - Schedule of Restricted Stock and Restricted Stock Units (Detail)	12 Months Ended
Dec. 31, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding, beginning balance	1,421,380
Granted, number of shares	504,738
Forfeited, number of shares	(3,044)
Vested, number of shares	(807,040)
Number of shares outstanding, ending balance	1,116,034
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding, beginning balance	54,165
Number of shares outstanding, ending balance	54,165
Weighted average grant date fair value, beginning of period \| $ / shares	$ 26.80
Weighted average grant date fair value, ending of period \| $ / shares	$ 26.80
Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding, beginning balance	70,276
Granted, number of shares	48,347
Vested, number of shares	(93,906)
Number of shares outstanding, ending balance	24,717
Weighted average grant date fair value, beginning of period \| $ / shares	$ 27.01
Granted, weighted average grant date fair value \| $ / shares	26.10
Vested, weighted average grant date fair value \| $ / shares	26.78
Weighted average grant date fair value, ending of period \| $ / shares	$ 26.10
Time-Based Restricted Stock Units Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding, beginning balance	468,958
Granted, number of shares	450,203
Forfeited, number of shares	(2,218)
Vested, number of shares	(288,429)
Number of shares outstanding, ending balance	628,514
Weighted average grant date fair value, beginning of period \| $ / shares	$ 19.61
Granted, weighted average grant date fair value \| $ / shares	27.40
Forfeited, weighted average grant date fair value \| $ / shares	27.00
Vested, weighted average grant date fair value \| $ / shares	20.61
Weighted average grant date fair value, ending of period \| $ / shares	$ 24.71
Performance Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding, beginning balance	827,981
Granted, number of shares	6,188
Forfeited, number of shares	(826)
Vested, number of shares	(424,705)
Number of shares outstanding, ending balance	408,638
Weighted average grant date fair value, beginning of period \| $ / shares	$ 17.73
Granted, weighted average grant date fair value \| $ / shares	26.08
Forfeited, weighted average grant date fair value \| $ / shares	19.33
Vested, weighted average grant date fair value \| $ / shares	17.05
Weighted average grant date fair value, ending of period \| $ / shares	$ 18.56

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

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)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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

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)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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).

+ 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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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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- 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

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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

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- Definition

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

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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.

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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