Derivatives - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended		9 Months Ended
	Sep. 30, 2014 Group I Swaps	Jan. 29, 2014 Group I Swaps	Sep. 30, 2014 Group II Swaps	Aug. 01, 2014 Group II Swaps
Derivative [Line Items]
Swaps, number of instruments held		4		3
Swaps, notional amount		$ 200,000		$ 220,000
Swaps, description of variable rate basis	1-month LIBOR		3-month LIBOR
Swaps, average fixed interest rate		2.29%		2.5795%