Schedule I - Condensed Financial Information of Registrant (Condensed Cash Flow Statement) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Net Cash Flows Provided by Operating Activities	$ 32,540	$ 103,380	$ 308,038
CASH FLOWS FROM INVESTING ACTIVITIES:
Sales of investments	1,350,003	1,760,336	1,118,957
Sales of property and equipment	24	0	19
Purchases of property and equipment	(73,101)	(64,260)	(34,791)
(Purchases) sales of restricted investments and other	5,466	(10,656)	22,522
Net cash provided by (used in) investing activities	(12,558)	222,227	(200,593)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net (decrease) increase in checks outstanding, net of deposits	23,842	(46,718)	45,909
Excess tax benefit on share-based compensation	6,089	1,349	571
Proceeds from exercise of stock options and employee stock purchases	16,941	13,356	3,644
Borrowings under financing arrangements	110,000	978,500	100,000
Repayments of borrowings under financing arrangements	122,500	872,212	316,771
Repurchase of common stock	(69,496)	(389,850)	(236,847)
Net cash (used in) provided by financing activities	89,875	(445,492)	(440,110)
Net (decrease) increase in cash and cash equivalents	109,857	(119,885)	(332,665)
Cash and cash equivalents, beginning of year	230,253	350,138	682,803
Cash and cash equivalents, end of year	340,110	230,253	350,138
SUPPLEMENTAL CASH FLOWS DISCLOSURE:
Interest paid	31,134	31,332	31,074
Income taxes paid	5,001	55,882	96,319
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Flows Provided by Operating Activities	165,141	252,100	155,740
CASH FLOWS FROM INVESTING ACTIVITIES:
Sales of investments	0	0	7,115
Sales of property and equipment	0	0	12
Purchases of property and equipment	(68,116)	(48,046)	(34,498)
Increase (decrease) in notes receivable from Subsidiaries	(7,000)	24,000	(26,200)
Capital contributions returned to Parent	1,500	1,796	1,182,635
Capital contributions tos subsidiaries	(17,560)	(400)	(120,972)
(Purchases) sales of restricted investments and other	876	(13,361)	14,253
Net cash provided by (used in) investing activities	(76,300)	(84,011)	1,074,745
CASH FLOWS FROM FINANCING ACTIVITIES:
Net (decrease) increase in checks outstanding, net of deposits	(44)	(37)	248
Excess tax benefit on share-based compensation	3,222	544	286
Net borrowings from subsidiaries	(9,103)	(14,246)	(1,144,992)
Proceeds from exercise of stock options and employee stock purchases	16,941	13,356	3,644
Borrowings under financing arrangements	110,000	978,500	100,000
Repayments of borrowings under financing arrangements	122,500	872,212	200,000
Repurchase of common stock	(69,496)	(389,850)	(236,847)
Net cash (used in) provided by financing activities	(70,980)	(283,945)	(1,477,661)
Net (decrease) increase in cash and cash equivalents	17,861	(115,856)	(247,176)
Cash and cash equivalents, beginning of year	87,948	203,804	450,980
Cash and cash equivalents, end of year	105,809	87,948	203,804
SUPPLEMENTAL CASH FLOWS DISCLOSURE:
Interest paid	31,134	31,332	31,074
Income taxes paid	$ 5,001	$ 55,882	$ 96,319