Repurchase Agreements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Repurchase Agreements [Abstract]
Maximum amount of outstanding agreements	$ 156.2	$ 144.3
Daily average amount of outstanding agreements	$ 149.9	$ 140.9
Maturity date	Sep. 13, 2020