Losses and Loss Adjustment Expenses - Total Losses and Loss Adjustment Expense Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Effects of Reinsurance [Line Items]
Outstanding losses	$ 3,656,218	$ 3,283,862
IBNR	3,137,075	2,584,612
Fair value adjustments	(151,786)	(148,325)
Total	6,641,507	5,720,149
Non-Life Run-Off Segment
Effects of Reinsurance [Line Items]
Outstanding losses	3,124,006	2,757,774
IBNR	2,501,564	1,991,009
Fair value adjustments	(166,354)	(163,329)
Total	5,459,216	4,585,454	$ 4,693,262	$ 3,435,010
Atrium
Effects of Reinsurance [Line Items]
Outstanding losses	68,124	68,913
IBNR	126,152	115,613
Fair value adjustments	15,643	16,491
Total	209,919	201,017	202,873	212,611
StarStone Segment
Effects of Reinsurance [Line Items]
Outstanding losses	464,088	457,175
IBNR	509,359	477,990
Fair value adjustments	(1,075)	(1,487)
Total	$ 972,372	$ 933,678	$ 828,488	$ 861,800

Liability for title claims and claims adjustment expense fair value adjustments.

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- Definition

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.

+ References

No definition available.

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- Definition

The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437

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- Definition

Estimated costs as of the balance sheet date of settling insured claims and costs incurred in the claims settlement process for claims that have not yet been submitted to the insurance company for reimbursement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.W)
-URI http://asc.fasb.org/extlink&oid=27015833&loc=d3e570705-122907

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- Definition

Costs of settling insured claims and costs incurred in the claims settlement process for the specified year specifically for claims that have already been submitted to the insurance company for reimbursement.

+ References

No definition available.

+ Details

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