Derivatives - Fair Value of Derivative Instruments (Detail) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2016		Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value at period end	[1]	$ (10.3)		$ (1.7)
Interest Rate Swap One [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		25.0
Fair Value at period end	[1]	$ 0.0		(0.1)
Interest Rate		1.10%
Maturity Date		Jul. 31, 2016
Interest Rate Swaps Two [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 28.1
Fair Value at period end	[1]	$ (0.1)		(0.2)
Interest Rate		1.38%
Maturity Date		Jan. 02, 2017
Interest Rate Swap Three PY [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value				33.0
Fair Value at period end	[1]			0.0
Interest Rate		3.72%
Maturity Date		Dec. 01, 2017
Interest Rate Swaps Three [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 48.0		(0.1)	[1]
Fair Value at period end	[1]	$ (0.4)
Interest Rate		1.12%
Interest Rate Swaps Four [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 7.6
Fair Value at period end	[1]	$ (0.1)		0.0
Interest Rate		1.00%
Maturity Date		Jan. 01, 2018
Interest Rate Swap Five [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 55.0
Fair Value at period end		$ (0.5)	[1]	0.1
Interest Rate		1.12%
Maturity Date		Jan. 01, 2018
Interest Rate Swap Six [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 30.0
Fair Value at period end		$ (0.9)	[1]	0.5
Interest Rate		1.78%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Seven [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.6)		(0.4)
Interest Rate		1.78%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Eight [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.6)		(0.3)
Interest Rate		1.78%
Maturity Date		Jan. 02, 2019
Interest Rate Swaps Nine [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.6)		(0.3)
Interest Rate		1.79%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Ten [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.6)		(0.3)
Interest Rate		1.79%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Eleven [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.6)		(0.3)
Interest Rate		1.79%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Twelve [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 25.0
Fair Value at period end	[1]	$ (0.3)		0.0
Interest Rate		1.16%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Thirteen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 25.0
Fair Value at period end	[1]	$ 0.3		0.0
Interest Rate		1.16%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Fourteen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 25.0
Fair Value at period end	[1]	$ 0.3		0.0
Interest Rate		1.16%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Fifteen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ 0.3		0.0
Interest Rate		1.16%
Maturity Date		Jan. 02, 2019
Interest Rate Swap Sixteen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.4)		0.1
Interest Rate		1.23%
Maturity Date		Jun. 26, 2020
Interest Rate Swap Seventeen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.4)		0.2
Interest Rate		1.23%
Maturity Date		Jun. 26, 2020
Interest Rate Swap Eighteen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.4)		0.2
Interest Rate		1.23%
Maturity Date		Jun. 26, 2020
Interest Rate Swap Nineteen [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.4)		0.2
Interest Rate		1.23%
Maturity Date		Jun. 26, 2020
Interest Rate Swap Twenty [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.4)		$ 0.2
Interest Rate		1.24%
Maturity Date		Jun. 26, 2020
Interest Rate Swap Twenty One [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 9.0
Fair Value at period end	[1]	$ (0.2)
Interest Rate		1.19%
Maturity Date		Feb. 01, 2021
Interest Rate Swap Twenty Three [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 35.0
Fair Value at period end	[1]	$ (0.3)
Interest Rate		1.016%
Maturity Date		Mar. 01, 2021
Interest Rate Swap Twenty Two [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 35.0
Fair Value at period end	[1]	$ (0.3)
Interest Rate		1.013%
Maturity Date		Mar. 01, 2021
Interest Rate Forward Starting Swap One [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 48.0
Fair Value at period end	[1]	$ (0.7)
Interest Rate		1.42%
DerivativeEffectiveDate		Jan. 02, 2018
Maturity Date		Feb. 01, 2021
Interest Rate Swap Twenty Six [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.2)
Interest Rate		1.018%
Maturity Date		Mar. 01, 2021
Interest Rate Swap Twenty Five [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.2)
Interest Rate		1.016%
Maturity Date		Mar. 01, 2021
Interest Rate Swap Twenty Four [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(in millions of dollars) Notional Value		$ 20.0
Fair Value at period end	[1]	$ (0.2)
Interest Rate		1.0145%
Maturity Date		Mar. 01, 2021

[1] As of June 30, 2016 and December 31, 2015, derivative valuations in their entirety were classified in Level 2 of the fair value hierarchy and we did not have any significant recurring fair value measurements related to derivative instruments using significant unobservable inputs (Level 3).(2) This interest rate swap was terminated effective March 23, 2016.