Income Taxes - Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Unrecognized Tax Benefits [Line Items]
Beginning balance	$ 13,576	$ 13,058	$ 13,084
Reductions
Reductions			(493)
Settlements
Lapses in statute of limitations	(137)
Ending balance	14,067	13,576	13,058
Federal [Member]
Unrecognized Tax Benefits [Line Items]
Tax positions related to current year, Additions	289	297	259
Tax positions related to prior year, Additions	37
State [Member]
Unrecognized Tax Benefits [Line Items]
Tax positions related to current year, Additions	$ 302	$ 221	$ 208