Supplementary Information on Loss and ALAE Development - Incurred and Paid Claims (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 193,271,387
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	156,930,790
Short-duration Insurance Contracts, Accident Year 2007 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	24,023,109,000	$ 23,979,026,000	$ 24,107,044,000	$ 24,770,214,000	$ 25,511,988,000	$ 26,203,117,000	$ 27,029,577,000	$ 27,061,323,000	$ 26,117,669,000	$ 24,747,856,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	24,023,106,000	23,907,436,000	23,906,841,000	23,762,758,000	23,548,201,000	23,333,861,000	21,637,121,000	18,309,573,000	12,283,217,000	$ 6,980,915,000
Short-duration Insurance Contracts, Accident Year 2008 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	17,617,589,000	17,456,810,000	17,889,384,000	18,668,518,000	19,347,265,000	20,004,073,000	21,290,931,000	22,106,937,000	22,580,220,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	17,593,260,000	17,178,322,000	17,041,185,000	17,001,061,000	16,856,762,000	15,902,618,000	13,950,969,000	9,869,827,000	$ 6,962,996,000
Short-duration Insurance Contracts, Accident Year 2009 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	18,554,526,000	19,050,348,000	19,667,376,000	20,398,961,000	21,012,811,000	21,571,780,000	21,412,289,000	21,751,337,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	17,550,304,000	17,380,065,000	17,336,454,000	17,121,818,000	16,180,346,000	13,160,200,000	9,592,059,000	$ 4,919,359,000
Short-duration Insurance Contracts, Accident Year 2010 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	17,641,161,000	18,075,737,000	18,639,537,000	19,326,007,000	19,883,812,000	20,437,443,000	21,418,368,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	16,778,214,000	16,283,050,000	15,330,864,000	14,756,510,000	12,955,467,000	10,695,223,000	$ 7,535,122,000
Short-duration Insurance Contracts, Accident Year 2011 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	18,224,634,000	17,879,595,000	17,014,895,000	17,605,460,000	17,900,250,000	18,120,563,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	17,422,583,000	16,115,802,000	14,251,525,000	11,212,490,000	8,608,287,000	$ 4,719,943,000
Short-duration Insurance Contracts, Accident Year 2012 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	18,050,131,000	18,344,175,000	18,895,666,000	19,532,022,000	18,511,598,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	16,734,967,000	15,369,629,000	13,411,125,000	11,673,621,000	$ 6,719,982,000
Short-duration Insurance Contracts, Accident Year 2013 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	21,742,580,000	20,323,841,000	20,118,343,000	19,570,946,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	19,067,334,000	14,319,057,000	10,656,777,000	$ 7,594,731,000
Short-duration Insurance Contracts, Accident Year 2014 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	14,930,960,000	15,394,995,000	16,884,731,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	9,173,947,000	6,082,893,000	$ 3,826,263,000
Short-duration Insurance Contracts, Accident Year 2015 [Member]
Claims Development [Line Items]
Cumulative Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	20,840,034,000	20,452,199,000
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 11,151,955,000	$ 6,263,796,000