SUMMARY OF DIFFERENCES BETWEEN THE COMPANY'S EFFECTIVE TAX RATE AND THE FEDERAL STATUTORY TAX RATE (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Percent of pretax earnings:
Statutory federal tax rate	35.00%	35.00%	35.00%
Increase (reduction) resulting from:
State income tax, net of federal tax benefit	3.50%	3.20%	3.10%
Other permanent differences	0.40%	0.10%	0.10%
International operations, net of foreign tax credits	3.80%	(0.50%)	0.00%
Worthless stock tax benefit	(3.40%)	(0.00%)	(0.00%)
Federal tax credits and income deductions	(2.50%)	(2.30%)	(2.10%)
Tax impact of uncertain tax positions and other	(0.90%)	(0.60%)	(1.10%)
Effective income tax rate	35.90%	34.90%	35.00%