Segment, Geographic Location, and Customer Information - Net Sales of 10% or More of Total Revenues Derived from Customers (Parenthetical) (Detail)	3 Months Ended	6 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Entity Wide Revenue Major Customer [Line Items]
Percentage of net sales	10.00%	10.00%	10.00%	10.00%

Entity wide revenue by major customer percent less than ten.

No definition available.

Name:	bzc_EntityWideRevenueByMajorCustomerPercentLessThanTen
Namespace Prefix:	bzc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration