Condensed Financial Information of Registrant (Parent Only) Balance Sheets (Detail) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Fixed maturities		$ 1,240,031	$ 1,306,149
Cash and cash equivalents		75,110	67,037	$ 58,823	$ 105,492
Receivable for Securities			172
Other assets		51,104	49,630
Total assets		1,972,946	1,957,294	1,930,033
Liabilities:
Debt		163,143	172,034
Other liabilities		45,761	53,344
Total liabilities		1,174,995	1,207,368
Commitments and contingencies
Shareholders' equity:
Ordinary shares, $0.0001 par value, 900,000,000 ordinary shares authorized; A ordinary shares issued and outstanding: 13,436,548; B ordinary shares issued and outstanding: 4,133,366		2	3
Additional paid-in capital		430,283	529,872
Accumulated other comprehensive income, net of tax		(618)	4,078	23,384
Retained earnings		368,284	318,416
Total shareholders' equity		797,951	749,926	908,290
Total liabilities and shareholders' equity		1,972,946	1,957,294
Ordinary Shares A
Shareholders' equity:
A ordinary shares in treasury, at cost: 3,110,795 shares			(102,443)
Total shareholders' equity		1	2	2	2
Parent Company
ASSETS
Fixed maturities		3,770
Cash and cash equivalents		91	2,185	$ 46	$ 1,746
Intercompany notes receivable	[1]	750,397
Equity in unconsolidated subsidiaries	[1]	292,195	951,760
Receivable for Securities		1
Due from affiliates	[1]		3,645
Other assets		59
Total assets		1,046,513	957,590
Liabilities:
Debt		96,497	96,388
Intercompany notes payable	[1]	141,998	108,000
Interest Payable		990
Due to affiliates	[1]	8,759
Other liabilities		318	3,221
Total liabilities		248,562	207,609
Commitments and contingencies
Shareholders' equity:
Ordinary shares, $0.0001 par value, 900,000,000 ordinary shares authorized; A ordinary shares issued and outstanding: 13,436,548; B ordinary shares issued and outstanding: 4,133,366		2	3
Deferred shares, €1 par value, 40,000 ordinary shares authorized, issued and outstanding	[1]		55
Preferred shares, $0.0001 par value, 100,000,000 shares authorized, none issued and outstanding
Additional paid-in capital		430,283	529,872
Accumulated other comprehensive income, net of tax		(618)	4,078
Retained earnings		368,284	318,416
Total shareholders' equity		797,951	749,981
Total liabilities and shareholders' equity		$ 1,046,513	957,590
Parent Company | Ordinary Shares A
Shareholders' equity:
A ordinary shares in treasury, at cost: 3,110,795 shares			$ (102,443)

[1] This item has been eliminated in the Company's Consolidated Financial Statements.