Reinsurance (Effect of Reinsurance on Net Premiums and Claims and Other Policy Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premiums Earned, Net [Abstract]
Direct Premiums Earned	$ 57,562	$ 43,106	$ 19,365
Assumed Premiums Earned	10,049,587	9,371,308	9,098,378
Ceded Premiums Earned	(858,278)	(843,673)	(447,889)
Net premiums	9,248,871	8,570,741	8,669,854
Policyholder Benefits and Claims Incurred, Net [Abstract]
Policyholder Benefits and Claims Incurred, Direct	105,435	82,942	32,564
Policyholder Benefits and Claims Incurred, Assumed	8,621,647	8,205,308	7,805,984
Policyholder Benefits and Claims Incurred, Ceded	(733,707)	(798,868)	(431,907)
Claims and other policy benefits	$ 7,993,375	$ 7,489,382	$ 7,406,641