Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		2 Months Ended	3 Months Ended																		12 Months Ended
		Feb. 26, 2016	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Net increase (decrease) in restricted cash																			$ (42,900)	$ 60,300	$ (17,212)		$ (228)		$ 17,440
Home office and equipment [Abstract]
Accumulated depreciation of home office and equipment			$ 26,100								$ 54,900								$ 53,000		26,100		54,900		53,000
Depreciation expense of home office and equipment																					$ 3,200		$ 2,200		$ 1,800
Loss Reserves [Abstract]
Threshold period for amortization																					1 year
Maximum age for qualified employees for both medical and dental benefits																					65 years
Share-Based Compensation [Abstract]
Minimum vesting period for share-based compensation awards (in years)																					1 year
Maximum vesting period for share-based compensation awards (in years)																					3 years
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from weighted average number of shares (in shares)																					0		54,500		130,100
Basic earnings (loss) per share [Abstract]
Net income (loss)			$ 102,418		$ 822,852		$ 113,654		$ 133,076		$ 74,428		$ 72,017		$ 45,522		$ 59,982				$ 1,172,000		$ 251,949		$ (49,848)
Average common shares outstanding (in shares)																					339,552		338,523		311,754
Basic income (loss) per share (in dollars per share)			$ 0.30	[1],[2]	$ 2.42	[1],[2]	$ 0.33	[1],[2]	$ 0.39	[1],[2]	$ 0.22	[1]	$ 0.21	[1]	$ 0.13	[1]	$ 0.18	[1]			$ 3.45	[1],[2]	$ 0.74	[1]	$ (0.16)
Diluted earnings (loss) per share [Abstract]
Net income (loss)			$ 102,418		$ 822,852		$ 113,654		$ 133,076		$ 74,428		$ 72,017		$ 45,522		$ 59,982				$ 1,172,000		$ 251,949		$ (49,848)
Diluted income available to common shareholders																					$ 1,214,942		$ 264,146		$ (49,848)
Weighted-average shares - Basic (in shares)																					339,552		338,523		311,754
Weighted-average shares - Diluted (in shares)																					468,039		413,522		311,754
Diluted income (loss) per share (in dollars per share)			$ 0.24	[1],[2]	$ 1.78	[1],[2]	$ 0.28	[1],[2]	$ 0.32	[1],[2]	$ 0.19	[1]	$ 0.18	[1]	$ 0.12	[1]	$ 0.15	[1]			$ 2.60	[1],[2]	$ 0.64	[1]	$ (0.16)
Convertible senior notes percentage (in hundredths)			2.00%																		2.00%
Federal statutory income tax rate (in hundredths)																					35.00%		35.00%		(35.00%)
Participating Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Participating securities included weighted average number of common shares outstanding (in shares)																					100		100
Antidilutive securities excluded from weighted average number of shares (in shares)																									100
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Participating securities included weighted average number of common shares outstanding (in shares)																					2,100		3,100
Home Office
Home office and equipment [Abstract]
Estimated useful life																					45 years
Equipment
Home office and equipment [Abstract]
Estimated useful life																					5 years
Data Processing Hardware
Home office and equipment [Abstract]
Estimated useful life																					3 years
Convertible Senior Notes - due April 2020
Diluted earnings (loss) per share [Abstract]
Interest expense, net of tax	[3]																				$ 7,928		$ 12,197		$ 0
Convertible debt common stock equivalents (in shares)																					71,917		71,917		0
Convertible senior notes percentage (in hundredths)			2.00%								2.00%										2.00%		2.00%
Convertible Senior Notes Due 2017
Diluted earnings (loss) per share [Abstract]
Interest expense, net of tax	[3]																				$ 12,228		$ 0		$ 0
Convertible debt common stock equivalents (in shares)																					25,603		0		0
Convertible senior notes percentage (in hundredths)			5.00%								5.00%										5.00%		5.00%
Extinguishment of debt, amount																					$ 11,500
Convertible Senior Notes Due 2017 | Subsequent Event
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from weighted average number of shares (in shares)		9,500
Diluted earnings (loss) per share [Abstract]
Extinguishment of debt, amount		$ 127,700
Convertible Junior Debentures at 9% per annum, Due 2063
Diluted earnings (loss) per share [Abstract]
Interest expense, net of tax	[3]																				$ 22,786		$ 0		$ 0
Convertible debt common stock equivalents (in shares)																					28,854		0		0
Convertible senior notes percentage (in hundredths)			9.00%																		9.00%
Convertible Junior Debentures at 9% per annum, Due 2063 | Subsequent Event
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from weighted average number of shares (in shares)		9,800
Diluted earnings (loss) per share [Abstract]
Extinguishment of debt, amount		$ 132,700
Unvested restricted stock units
Diluted earnings (loss) per share [Abstract]
Unvested restricted stock (in shares)																					2,113		3,082		0

[1] Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of the quarterly per share data may not equal the per share data for the year.

[2] In periods where convertible debt instruments are dilutive to earnings per share the “if-converted” method of computing diluted EPS requires an interest expense adjustment, net of tax, to net income available to shareholders. The interest expense adjustment was not tax effected for all 2014 periods presented due to our valuation allowance on deferred tax assets. See Note 3 – “Summary of Significant Accounting Policies” for further discussion.

[3] The year ended December 31, 2015 has been tax effected at a rate of 35%. Due to the valuation allowance recorded against deferred tax assets the year ended December 31, 2014 was not tax effected.