INCOME TAXES: (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of federal income taxes at the applicable statutory rate to the recorded provision from continuing operations
Federal statutory rate (as a percent)	35.00%	35.00%	35.00%
Amount of valuation allowance for deferred tax asset of consolidated VIEs released	$ 7.7
Number of variable interest entities for which the valuation allowance released	1
Adjustments-
State income taxes, net of federal tax benefit (as a percent)	1.30%	1.70%	1.50%
Non-deductible expenses (as a percent)	0.30%	0.40%	0.40%
Basis in subsidiaries stock (as a percent)			(2.10%)
Taxes on consolidated VIEs (as a percent)	(3.40%)	(0.70%)	(1.20%)
Other (as a percent)	(1.20%)	0.60%	0.80%
Effective income tax rate (as a percent)	32.00%	37.00%	34.40%
Tax effect of non-deductible expense items
Deferred tax benefit related to recovery of historical losses attributable to the basis in stock of certain subsidiaries			$ 2.5