Reinsurance (Tables)

12 Months Ended

Dec. 31, 2017

Reinsurance Disclosures [Abstract]

Ceded reinsurance

Assumed, ceded and net amounts for the years ended December 31, 2017, 2016 and 2015 were as follows (in thousands of U.S. dollars):

	Premiums Written		Premiums Earned		Losses and  Loss Expenses
2017
Assumed	$	5,587,894	$	5,471,546	$	4,458,290
Ceded	467,968		446,565		617,308
Net	$	5,119,926	$	5,024,981	$	3,840,982
2016
Assumed	$	5,356,942	$	5,343,831	$	3,412,648
Ceded	403,472		374,235		164,557
Net	$	4,953,470	$	4,969,596	$	3,248,091
2015
Assumed	$	5,547,525	$	5,570,321	$	3,215,665
Ceded	317,977		301,143		58,245
Net	$	5,229,548	$	5,269,178	$	3,157,420