Variable Interest Entities - Schedule of Carrying Value of Assets and Liabilities Eliminated from Financial Statement (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Feb. 28, 2013	Dec. 31, 2012	Jun. 30, 2012
Receivables [Abstract]
Other assets		$ 6,614
Total assets	767,578	6,614	675,204	558,651
Other current liabilities	43,177	3,060	106,796	33,091
Other liabilities		43,054
Total liabilities	$ 637,892	$ 46,114	$ 549,439	$ 474,621