Schedule II - Condensed Financial Information of Registrant - Condensed Statements of Cash Flows of Registrant (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income (loss)	$ 101,700,000	$ (69,000,000)	$ 110,700,000
Adjustments to reconcile net income (loss) to operating cash flows:
Depreciation and amortization	302,600,000	358,700,000	268,300,000
Stock compensation	91,100,000	61,500,000	31,200,000
Amortization of debt issuance costs	21,000,000	18,100,000	12,800,000
Amortization of debt discount	4,600,000	3,000,000	1,300,000
Write-off of debt issuance costs on retired debt	6,400,000	32,400,000	2,900,000
Write-off of debt discount on retired debt	2,800,000	(3,100,000)	(500,000)
Equity in net income of subsidiaries
Gain On Contingent Purchase Price Adjustment	(500,000)		(41,000,000)
Changes in operating assets and liabilities:
Net change in cash due to operating activities	607,900,000	522,300,000	622,500,000
Cash flows from investing activities:
Proceeds from investments sold, matured or repaid	5,609,200,000	9,432,200,000	6,206,700,000
Cost of investments acquired	(7,221,400,000)	(8,940,800,000)	(5,972,700,000)
Capital expenditures	(98,200,000)	(100,100,000)	(53,500,000)
Net change in cash due to investing activities	(1,920,600,000)	(2,010,800,000)	(185,600,000)
Cash flows from financing activities:
Dividends paid on preferred stock	(28,600,000)	(33,400,000)	(23,600,000)
Repayment of senior secured notes, including tender / call premium			0
Common stock repurchased	(65,600,000)	(12,300,000)
Share based award tax withholding payments	(31,500,000)	(22,300,000)	(3,900,000)
Other financing activities, net	2,800,000		(1,000,000)
Net change in cash due to financing activities	740,400,000	1,922,000,000	(102,700,000)
Net change in cash and cash equivalents	(580,500,000)	429,000,000	333,300,000
Cash and cash equivalents at beginning of period	1,899,700,000	1,470,700,000	1,137,400,000
Cash and cash equivalents at end of period	1,319,200,000	1,899,700,000	1,470,700,000
HGI
Cash flows from operating activities:
Net income (loss)	(10,300,000)	(45,800,000)	89,500,000
Adjustments to reconcile net income (loss) to operating cash flows:
Depreciation and amortization	200,000	200,000	100,000
Stock compensation	27,000,000	11,700,000	1,900,000
Amortization of debt issuance costs	3,500,000	2,700,000	2,900,000
Amortization of debt discount	1,500,000	500,000	600,000
Write-off of debt issuance costs on retired debt	0	10,800,000	0
Write-off of debt discount on retired debt	0	2,100,000	0
Deferred income taxes	0	0	3,600,000
Equity in net income of subsidiaries	(207,700,000)	(263,700,000)	(354,600,000)
Dividends from subsidiaries	118,000,000	127,100,000	69,500,000
Loss from the change in the fair value of the equity conversion feature of preferred stock	12,700,000	101,600,000	156,600,000
Gain On Contingent Purchase Price Adjustment	(500,000)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	0	0	(4,600,000)
Accounts payable and accrued and other current liabilities	43,500,000	51,400,000	27,000,000
Other operating	(700,000)	11,600,000	(1,700,000)
Net change in cash due to operating activities	(12,800,000)	10,200,000	(9,200,000)
Cash flows from investing activities:
Proceeds from investments sold, matured or repaid	0	34,000,000	108,900,000
Cost of investments acquired	0	0	(68,000,000)
Capital contributions to consolidated subsidiaries	(115,500,000)	(454,400,000)	(36,300,000)
Return of capital from subsidiary	0	126,800,000	88,000,000
(Advances to) repayments from consolidated subsidiaries	0	0	49,300,000
Capital expenditures	(300,000)	(400,000)	0
Net change in cash due to investing activities	(115,800,000)	(294,000,000)	141,900,000
Cash flows from financing activities:
Dividends paid on preferred stock	(28,600,000)	(33,400,000)	(31,700,000)
Proceeds from senior secured notes	400,000,000	923,900,000	0
Repayment of senior secured notes, including tender / call premium	0	(545,900,000)
Debt issuance costs	(10,400,000)	(25,100,000)	0
Common stock repurchased	(65,600,000)	(12,300,000)
Share based award tax withholding payments	(6,500,000)	(2,300,000)
Other financing activities, net	2,800,000	0	0
Net change in cash due to financing activities	291,700,000	304,900,000	(31,700,000)
Net change in cash and cash equivalents	163,100,000	21,100,000	101,000,000
Cash and cash equivalents at beginning of period	256,900,000	235,800,000	134,800,000
Cash and cash equivalents at end of period	$ 420,000,000	$ 256,900,000	$ 235,800,000