Commitment Fee Under Credit Facilities (Detail)	12 Months Ended
	Dec. 31, 2015
Range One [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.40%
Letter Of Credit Fee	3.00%
Range One [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.00%
Range One [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	3.00%
Range Two [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.35%
Letter Of Credit Fee	2.50%
Range Two [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	1.50%
Range Two [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.50%
Range Three [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.30%
Letter Of Credit Fee	2.00%
Range Three [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	1.00%
Range Three [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.00%
Range Four [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.25%
Letter Of Credit Fee	1.50%
Range Four [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	0.50%
Range Four [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	1.50%