Equity-Based Compensation (Summary of Information about Restricted Stock Units and Weighted Average Grant Date Fair Value) (Details) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted stock units
Restricted Stock Units / Restricted Stock (in shares)
Balance at beginning of period (in shares)	536,164
Granted (in shares)	133,548	141,982	212,419
Vested (in shares)	(202,788)
Forfeited (in shares)	(25,108)
Balance at end of period (in shares)	441,816	536,164
Weighted Average Grant Date Fair Value (in dollars per share)
Balance at beginning of period (in USD per share)	$ 17.79
Granted (in USD per share)	36.56	$ 25.44	$ 17.78
Vested (in USD per share)	15.71
Forfeited (in USD per share)	25.88
Balance at end of period (in USD per share)	$ 23.96	$ 17.79
Restricted shares
Restricted Stock Units / Restricted Stock (in shares)
Balance at beginning of period (in shares)	7,361
Granted (in shares)	2,034	3,185	21,318
Vested (in shares)	(5,137)
Forfeited (in shares)	0
Balance at end of period (in shares)	4,258	7,361
Weighted Average Grant Date Fair Value (in dollars per share)
Balance at beginning of period (in USD per share)	$ 17.07
Granted (in USD per share)	34.42	$ 29.30	$ 17.48
Vested (in USD per share)	23.75
Forfeited (in USD per share)	0.00
Balance at end of period (in USD per share)	$ 17.30	$ 17.07
Performance stock units
Restricted Stock Units / Restricted Stock (in shares)
Balance at beginning of period (in shares)	396,714
Granted (in shares)	108,748	0	396,714
Vested (in shares)	0
Forfeited (in shares)	(25,000)
Balance at end of period (in shares)	480,462	396,714
Weighted Average Grant Date Fair Value (in dollars per share)
Balance at beginning of period (in USD per share)	$ 19.78
Granted (in USD per share)	42.72	$ 0.00	$ 19.78
Vested (in USD per share)	0.00
Forfeited (in USD per share)	25.44
Balance at end of period (in USD per share)	$ 24.68	$ 19.78
Deferred stock units
Restricted Stock Units / Restricted Stock (in shares)
Balance at beginning of period (in shares)	11,945
Granted (in shares)	10,170	11,945	0
Vested (in shares)	0
Forfeited (in shares)	0
Balance at end of period (in shares)	22,115	11,945
Weighted Average Grant Date Fair Value (in dollars per share)
Balance at beginning of period (in USD per share)	$ 29.30
Granted (in USD per share)	34.42	$ 29.30	$ 0.00
Vested (in USD per share)	0.00
Forfeited (in USD per share)	0.00
Balance at end of period (in USD per share)	$ 31.65	$ 29.30

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=96867065&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=96867065&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=96867065&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=96867065&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=96867065&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.

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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=96867065&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=96867065&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
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-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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