Schedule I - Condensed Financial Information of Registrant (Condensed Balance Sheet) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 869,133,000	$ 433,155,000	$ 340,110,000	$ 230,253,000
Available for sale securities	1,791,060,000	1,567,020,000
Other assets	220,122,000	132,683,000
Deferred taxes	57,911,000	94,060,000
Assets held for sale	50,000,000	0
Total current assets	4,515,617,000	2,919,890,000
Property and equipment, net	84,328,000	201,395,000
Goodwill	558,886,000	565,886,000	565,900,000
Other intangible assets, net	11,822,000	13,842,000
Deferred taxes	33,081,000	5,793,000
Other assets	187,630,000	162,551,000
Total Assets	5,395,934,000	3,929,125,000
Current Liabilities:
Other current liabilities	71,988,000	72,098,000
Total current liabilities	2,944,503,000	1,577,178,000
Other noncurrent liabilities	242,705,000	213,427,000
Total Liabilities	3,686,712,000	2,300,314,000
Commitments and contingencies
Stockholders’ Equity:
Common stock	153,000	150,000
Additional paid-in capital	1,444,705,000	1,377,624,000
Treasury common stock, at cost	(2,341,652,000)	(2,179,744,000)
Retained earnings	2,609,277,000	2,463,648,000
Accumulated other comprehensive income	(3,261,000)	(32,867,000)	27,000,000	16,600,000
Total Stockholders' Equity	1,709,222,000	1,628,811,000	1,557,030,000	1,443,146,000
Total Liabilities and Stockholders' Equity	5,395,934,000	3,929,125,000
Parent Company [Member]
Current Assets:
Cash and cash equivalents	61,212,000	131,350,000	105,809,000	87,948,000
Available for sale securities	0	78,242,000
Other assets	36,740,000	30,965,000
Deferred taxes	11,538,000	16,158,000
Assets held for sale	50,000,000	0
Due from subsidiaries	128,967,000	177,957,000
Total current assets	288,457,000	434,672,000
Property and equipment, net	53,016,000	162,679,000
Goodwill	312,732,000	319,732,000
Other intangible assets, net	573,000	1,198,000
Investment in subsidiaries	3,060,191,000	2,608,631,000
Deferred taxes	36,453,000	6,523,000
Other assets	70,760,000	71,661,000
Total Assets	3,822,182,000	3,605,096,000
Current Liabilities:
Due to subsidiaries	284,654,000	237,555,000
Deferred taxes	34,684,000	0
Other current liabilities	130,580,000	100,755,000
Total current liabilities	449,918,000	338,310,000
Intercompany Notes Payable, long term	1,047,947,000	977,233,000
Long term debt	499,504,000	499,300,000
Other noncurrent liabilities	115,591,000	161,442,000
Total Liabilities	2,112,960,000	1,976,285,000
Commitments and contingencies
Stockholders’ Equity:
Common stock	153,000	150,000
Additional paid-in capital	1,444,705,000	1,377,624,000
Treasury common stock, at cost	(2,341,652,000)	(2,179,744,000)
Retained earnings	2,609,277,000	2,463,648,000
Accumulated other comprehensive income	(3,261,000)	(32,867,000)
Total Stockholders' Equity	1,709,222,000	1,628,811,000
Total Liabilities and Stockholders' Equity	$ 3,822,182,000	$ 3,605,096,000