Commitment Fee Under Credit Facilities (Detail)	12 Months Ended
	Dec. 31, 2014
Range One [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.50%
Range One [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.25%
Range One [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	3.25%
Range Two [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.50%
Range Two [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.00%
Range Two [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	3.00%
Range Three [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.50%
Range Three [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	1.75%
Range Three [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.75%
Range Four [Member]
Line of Credit Facility [Line Items]
Commitment Fee	0.45%
Range Four [Member] | Abr Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	1.50%
Range Four [Member] | Eurodollar Loans [Member]
Line of Credit Facility [Line Items]
Margin on Loans	2.50%