Taxation - Components of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 259,851	$ 255,151
Tax credits and other carryforwards	6,354	6,363
Insurance reserves	160,554	167,338
Lloyd's underwriting losses taxable in future periods	17,768	19,193
Provisions for bad debt	17,694	22,102
Other deferred tax assets	26,805	25,855
Gross deferred tax assets	489,026	496,002
Valuation allowance	(367,991)	(408,394)
Deferred tax assets	121,035	87,608
Deferred tax liabilities:
Unrealized gains on investments	(49,649)	(63,060)
Intangible assets	(20,895)	(18,000)
Other deferred tax liabilities	(22,044)	0
Deferred tax liabilities	(92,588)	(81,060)
Net deferred tax assets	$ 28,447	$ 6,548