Goodwill and Other Intangible Assets (Goodwill And Other Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, Gross	$ 1,900,727		$ 1,900,727	$ 1,899,159
Goodwill, Accumulated Impairment	(113,076)		(112,934)	(112,934)
Goodwill, Total	1,787,651		1,787,793	1,786,225
Goodwill, Net additions			1,568
Goodwill, reductions	(142)	$ 0
Finite-lived Intangible Assets [Roll Forward]
Other Intangible Assets, Gross	113,471		113,471	113,471
Other Intangible Assets, Accumulated Amortization	(70,523)		(67,963)	(56,738)
Other Intangible Assets, Net	42,948		45,508	$ 56,733
Other Intangible Assets, Amortization	$ (2,560)	$ (2,806)	$ (11,225)