Acquisitions and Disposals - Transaction Related Costs - Catlin (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Liabilities at December 31, 2016	$ 36,966
Costs incurred in 2017	73,067
2017 payments	89,880
Liabilities at December 31, 2017	20,153
Severance related costs
Business Acquisition [Line Items]
Liabilities at December 31, 2016	25,360
Costs incurred in 2017	19,794
2017 payments	37,354
Liabilities at December 31, 2017	7,800
Retention and other compensation costs
Business Acquisition [Line Items]
Liabilities at December 31, 2016	4,481
Costs incurred in 2017	9,561
2017 payments	13,744
Liabilities at December 31, 2017	298
Facilities-related costs
Business Acquisition [Line Items]
Liabilities at December 31, 2016	18
Costs incurred in 2017	11,051
2017 payments	4,574
Liabilities at December 31, 2017	6,495
Consulting and other
Business Acquisition [Line Items]
Liabilities at December 31, 2016	7,107
Costs incurred in 2017	32,661
2017 payments	34,208
Liabilities at December 31, 2017	$ 5,560

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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- Definition

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

+ References

No definition available.

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- Definition

The amount of liabilities recognized recorded in a transaction with the acquiree for each transaction that is recognized separately from the acquisition of assets and assumptions of liabilities in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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- Definition

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585

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