Components of Carrying Value of Residential Available for Sale Securities in Unrealized Loss Position (Detail) (Residential, USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Residential
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Consecutive Months Amortized Cost	$ 300,804	$ 607,030
Less Than 12 Consecutive Months Gross Unrealized Losses	(2,691)	(21,195)
Less Than 12 Consecutive Months Fair Value	298,113	585,835
12 Consecutive Months or Longer Amortized Cost	122,012	19,828
12 Consecutive Months or Longer Gross Unrealized Losses	(4,478)	(1,938)
12 Consecutive Months or Longer Fair Value	$ 117,534	$ 17,890