Investments (Limited Partnership Investments) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Investments [Line Items]
Recognized investment income (loss)			$ 54	$ (2,862)
Maximum exposure loss relating to VIE	$ 4,940		4,940		$ 4,787
Cash distributions	384
Limited Partnership [Member]
Schedule of Investments [Line Items]
Recognized investment income (loss)	1,119	$ (2,400)	54	$ (2,862)
Company's contributed capital to the partnership	31,946		31,946		27,276
Maximum exposure loss relating to VIE	$ 28,226		$ 28,226		$ 23,930