COMMON STOCK: (Details) (USD $)	5 Months Ended		11 Months Ended	12 Months Ended			1 Months Ended	0 Months Ended	1 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2015	May 07, 2013	Jan. 31, 2015	Oct. 12, 2013	Oct. 12, 2012	Oct. 11, 2013
Common Stock
Quarterly dividend declared (in dollars per share)	$ 0.165	$ 0.15	$ 0.15	$ 0.63	$ 0.60	$ 1.54
Dividend paid (in dollars per share)					$ 0.60
Net proceeds from public offering					$ 472,913,000
Number of shares repurchased				4,900,000
Total remaining authorization amount				134,400,000
Value of shares repurchased				133,157,000
6.125% Senior Unsecured Notes, due 2022
Common Stock
Interest rate (as a percent)	6.125%		6.125%	6.125%	6.125%					6.125%	6.125%
5.375% Senior Unsecured Notes, due 2021
Common Stock
Interest rate (as a percent)	5.375%		5.375%	5.375%	5.375%
6.375% Senior Notes, due 2021
Common Stock
Interest rate (as a percent)	6.375%		6.375%	6.375%	6.375%							6.375%
5.625% Senior Notes, due
Common Stock
Interest rate (as a percent)	5.625%		5.625%	5.625%	5.625%
Bank Credit Agreement
Common Stock
Unrestricted Cash First Lien Indebtedness Ratio				4.00
Amount of unrestricted annual cash payments	200,000,000			200,000,000
Amount of unrestricted annual cash payments to be carry over to next year	50,000,000			50,000,000
Additional aggregate basket				250,000,000
Aggregate basket as long as no Event	50,000,000			50,000,000
Bank Credit Agreement | Maximum
Common Stock
Unrestricted Cash First Lien Indebtedness Ratio				3.75
Subsequent Event
Common Stock
Quarterly dividend declared (in dollars per share)							$ 0.165
Class A Common Stock
Common Stock
Number of votes holders of common stock are entitled for each share held				1
Shares sold public offering					18,000,000			18,000,000
Offering price (in dollars per share)								$ 27.25
Net proceeds from public offering								472,900,000
Number of shares repurchased				4,876,121
Value of shares repurchased				48,000
Class A Common Stock | Subsequent Event
Common Stock
Number of shares repurchased									300,000
Value of shares repurchased									$ 7,800,000
Class B Common Stock
Common Stock
Number of votes holders of common stock are entitled for each share held				10
Number of Class B shares converted into Class A Common stock				100,000	2,905,502