Income Taxes - Additional Information (Detail) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
Tax Credit Carryforward [Line Items]
NOL allocated amount	$ 4,975,650
Operating tax carryforward expiration year start	2029
Operating tax carryforward expiration year end	2034
Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
NOL allocated amount	$ 4,718,447
United Kingdom [Member]
Tax Credit Carryforward [Line Items]
NOL allocated amount	103,598
Capital Loss Carryforward [Member] | United States [Member]
Tax Credit Carryforward [Line Items]
NOL allocated amount	$ 153,605