Minimum Lease Payments (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2016
Minimum
Capital Leases And Operating Leases [Line Items]
Capital leases, future minimum payments, interest included in payments, interest rate	2.00%
Maximum
Capital Leases And Operating Leases [Line Items]
Capital leases, future minimum payments, interest included in payments, interest rate	3.10%