Schedule I - Condensed Statements of Operations (Parent Company Only) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
REVENUE
Total revenue									$ 2,064,733	$ 1,994,013	$ 1,919,638
OPERATING EXPENSES
Professional services									42,663	43,958	48,324
Other									81,507	38,099	39,715
Total operating expenses	539,536	399,236	449,467	380,306	565,890	382,080	392,377	448,216	1,768,545	1,788,563	1,594,013
NET INCOME	52,796	62,748	31,921	17,649	(4,106)	33,673	34,162	29,056	165,114	92,785	190,559
Parent Company [Member]
REVENUE
Equity in earnings of subsidiaries									103,769	20,598	109,294
Interest and other income									58,227	65,319	67,042
Total revenue									161,996	85,917	176,336
OPERATING EXPENSES
Professional services									1,662	1,477	1,276
Other									122	131	143
Total operating expenses									1,784	1,608	1,419
NET INCOME									$ 160,212	$ 84,309	$ 174,917