Equity - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015
Restricted stock
Restricted stock awards
Compensation expense, vested awards	$ 2,012	$ 2,073
Restricted stock \| 2008 Plan
Restricted stock awards
Number of shares cancelled (in shares)		640
Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted	127,087	92,150
Nonvested awards
Number of Awards	211,553
Remaining compensation expense	$ 7,988
2016 \| Restricted stock
Nonvested awards
Number of Awards	980
Remaining compensation expense	$ 2,253
2017 \| Restricted stock
Nonvested awards
Number of Awards	85,343
Remaining compensation expense	$ 3,428
2018 \| Restricted stock
Nonvested awards
Number of Awards	49,352
Remaining compensation expense	$ 2,071
2019 \| Restricted stock
Nonvested awards
Number of Awards	75,878
Remaining compensation expense	$ 236
2019 \| Performance based stock units
Nonvested awards
Number of Awards	54,107
Grant Date Price $43.24 \| Three year vesting \| Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted	65,300
Granted (in dollars per share)	$ 43.24
Vesting period	3 years
Grant Date Price $43.24 \| TSR Targets \| Restricted stock and performance-based stock units
Restricted stock awards
Vesting period	3 years 8 months 12 days
Grant Date Price $43.24 \| Accelerated TSR Targets \| Restricted stock and performance-based stock units
Restricted stock awards
Vesting period	2 years 8 months 12 days
Grant Date Price $46.87 \| TSR Targets \| Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted	54,107
Granted (in dollars per share)	$ 46.87
Grant Date Price $46.87 \| Vesting Date, June 1, 2017 \| Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted	7,680
Granted (in dollars per share)	$ 46.87
Grant Date Price $44.45 \| Three year vesting \| Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted		65,750
Granted (in dollars per share)		$ 44.45
Vesting period		3 years
Grant Date Price $42.30 \| Three year vesting \| Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted		18,000
Granted (in dollars per share)		$ 42.30
Vesting period		3 years
Grant Date Price $42.30 \| Vesting Date, June 2, 2016 \| Restricted stock and performance-based stock units
Restricted stock awards
Number of shares granted		8,400
Granted (in dollars per share)		$ 42.30

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section F

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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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- Definition

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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- References

No definition available.

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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 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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- References

No definition available.

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