Segment Information - Summary of Company's Assets by Segment (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 8,709,307	$ 8,620,155
Non-Life Run-Off [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	6,432,340	6,619,992
Active Underwriting [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	899,476	585,176
Life and Annuities [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,377,491	$ 1,414,987