Deposit contracts (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of deposit contracts
Balance, beginning of period	$ 121,374	$ 120,946	$ 50,446
Consideration received	0	66,369
Net investment expense allocation and change in fair value of embedded derivatives	528	4,731
Payments	(100)	(600)
Balance, end of period	$ 121,374	$ 120,946	$ 50,446
Minimum
Deposit Contracts [Line Items]
Aggregate excess of loss agreement, crediting rate	2.50%
Aggregate excess of loss agreement, variable crediting rate	6.10%
Maximum
Deposit Contracts [Line Items]
Aggregate excess of loss agreement, crediting rate	3.00%
Aggregate excess of loss agreement, variable crediting rate	6.50%