Cost and Estimated Current Fair Value of Fixed-Income Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, cost basis	$ 24,112
Due between one and five years, cost basis	15,271
Total fixed income securities, cost basis	39,383
Due in one year or less, Estimated fair value	24,101
Due between one and five years, Estimated fair value	15,202
Total fixed income securities, Estimated fair value	$ 39,303