Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Significant Non-Cash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Change in Cash and Cash Equivalents due to reclass from Restricted Cash		$ 33,000	$ 32,200
Cash paid during the period for:
Interest	$ 37,652	37,542	25,115
Income taxes	143,111	132,874	118,290
Significant non-cash investing and financing activities
Other payables issued for purchased customer accounts	10,664	10,029	1,930
Estimated acquisition earn-out payables and related charges	4,463	36,899	33,229
Notes Assumed	492	0	0
Notes received on the sale of fixed assets and customer accounts	$ 22	$ 7,755	$ 6,340