Investments in debt and equity securities available-for-sale - Debt Securities According to Contractual Terms (Detail) $ in Thousands	Mar. 31, 2016 USD ($)
Amortized costs
In one year or less	$ 46,184
After one year through five years	248,586
After five years through ten years	217,047
After ten years	63,639
Amortized costs, total	575,456
Fair values
In one year or less	46,308
After one year through five years	256,004
After five years through ten years	224,775
After ten years	67,342
Fair values, total	$ 594,429