Incentive and Restricted Stock Plan and Dividend Reinvestment Plan - Summary of Non-Vested Restricted Stock (Detail) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Nonvested, Number of Shares (shares) [Roll Forward]
Granted, Restricted Stock (in shares)			3,247
2003 Stock Plan
Nonvested, Number of Shares (shares) [Roll Forward]
Granted, Restricted Stock (in shares)	259,673
2003 Stock Plan \| Restricted Stock
Nonvested, Number of Shares (shares) [Roll Forward]
Beginning of period (in shares)	23,145	79,415
Granted, Restricted Stock (in shares)	0	0
Vested, Restricted Stock (in shares)	15,433	41,740
Forfeited, Restricted Stock (in shares)	7,712	14,530
End of period (in shares)	0	23,145	79,415
Nonvested shares, Weighted Average Grant Date Fair Value (dollars per share) [Abstract]
Beginning of period (in dollars per share)	$ 23.28	$ 21.50
Granted (in dollar per share)	0.00	0.00
Vested (in dollar per share)	22.34	20.70
Forfeited (in dollar per share)	22.34	20.97
End of period (in dollars per share)	$ 0.00	$ 23.28	$ 21.50
2014 Stock Plan
Nonvested, Number of Shares (shares) [Roll Forward]
Granted, Restricted Stock (in shares)	168,296
2014 Stock Plan \| Restricted Stock
Nonvested, Number of Shares (shares) [Roll Forward]
Beginning of period (in shares)	79,824	0
Granted, Restricted Stock (in shares)	87,841		80,455
Vested, Restricted Stock (in shares)	14,126		158
Forfeited, Restricted Stock (in shares)	3,183		473
End of period (in shares)	150,356	79,824	0
Nonvested shares, Weighted Average Grant Date Fair Value (dollars per share) [Abstract]
Beginning of period (in dollars per share)	$ 23.24	$ 0.00
Granted (in dollar per share)	28.71		$ 23.24
Vested (in dollar per share)	23.57		23.19
Forfeited (in dollar per share)	26.15		23.19
End of period (in dollars per share)	$ 26.34	$ 23.24	$ 0.00

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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- 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

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 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

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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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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+ References

No definition available.

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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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