Commitments - Credit Facility (Details) (USD $)	1 Months Ended
	Jan. 31, 2014
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 50,000,000
Undrawn commitment fee percentage	0.175%
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 15,000,000
Base Rate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Stated rate	1.50%
Federal Funds Rate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Eurodollar [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.00%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.50%