Policy Claims and Benefits (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Liability for Claims and Claims Adjustment Expense	$ 6,584,668	$ 5,896,469
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	(432,582)	(455,547)
Liability For Unpaid Claims And Claims Adjustment Expense Net Of Recoverable	6,152,086	5,440,922
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Current Year Claims and Claims Adjustment Expense	8,203,842	7,534,297
Prior Year Claims and Claims Adjustment Expense	108,023	97,336
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	8,311,865	7,631,633
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year	(2,937,099)	(2,748,547)
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years	(4,774,623)	(4,222,550)
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid	(7,711,722)	(6,971,097)
Liability for Unpaid Claims and Claims Adjustment Expense, Interest Accretion	19,887	18,550
Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss)	(99,788)	(153,247)
Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments	(79,901)	(134,697)
Liability For Unpaid Claims And Claims Adjustment Expense Net Of Recoverable	6,672,328	5,966,761
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	508,003	424,545
Liability for Claims and Claims Adjustment Expense	$ 7,180,331	$ 6,391,306