Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

No definition available.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (a)(1)
-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 were forfeited 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)(1)(iv)(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 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 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

Intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options.

+ References

No definition available.

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Stock-Based Compensation Plans - Restricted stock activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
The 2007 plan
Number Outstanding
Balance at the beginning of the period (in shares)	396,595	525,356	515,130
Shares granted	136,645	146,440	237,708
Shares vested	(213,528)	(275,201)	(221,732)
Shares cancelled	(20,377)		(5,750)
Balance at the end of the period (in shares)	299,335	396,595	525,356
Intrinsic value of unvested awards (in dollars)	$ 6,058,336	$ 7,131,200	$ 8,786,611	$ 7,060,474
The 2007 plan \| Restricted stock
Number Outstanding
Balance at the beginning of the period (in shares)	396,595	525,356	515,130
Shares vested	(213,528)	(275,201)	(221,732)
Shares cancelled	(20,377)		(5,750)
Balance at the end of the period (in shares)	299,335	396,595	525,356
Remaining average vesting period for recognition of unrecognized compensation expense	1 year 6 months
Unrecognized compensation expense (in dollars)	$ 3,800,000
The 2007 plan \| Restricted stock \| Awards Vesting Over Two Year Member
Number Outstanding
Shares granted	20,000
Vesting period	2 years
The 2007 plan \| Restricted stock \| Awards Vesting Over Three Years [Member]
Number Outstanding
Shares granted	85,000	125,000	174,500
Vesting period	3 years	3 years	3 years
The 2007 plan \| Restricted stock \| Awards vesting over four years [Member]
Number Outstanding
Shares granted	13,250	5,000	13,000
Vesting period	4 years	4 years	4 years
The 2007 plan \| Restricted stock \| Awards vesting on first anniversary
Number Outstanding
Shares granted		16,440	50,208
The 2007 plan \| Restricted Stock Four Year Vesting [Member] \| Awards vesting on first anniversary
Number Outstanding
Shares granted	18,395
1996 Plan
Number Outstanding
Vesting period	10 years