Summary of Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Supplemental Cash Flow Elements [Abstract]
Interest	$ 7,660	$ 7,764
Income taxes	52,077	45,261
Other payable issued for purchased customer accounts	257	23,594
Notes payable issued or assumed for purchased customer accounts		59
Estimated acquisition earn-out payables and related charges	2,554	12,919
Notes received on the sale of fixed assets and customer accounts	$ 614	$ 1,273