Impact on Previously Issued Financial Statements for the Correction of an Error, Revised Consolidated Statement of Shareholders' Equity (Details) - USD ($)	3 Months Ended					6 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Consolidated Statement of Shareholders' Equity [Abstract]
Balance at beginning of period		$ 78,510,000				$ 78,510,000
Net income (loss)	$ 3,513,000			$ 5,595,000	$ 7,820,000	(1,982,000)	$ 13,415,000
Balance at end of period	77,274,000					77,274,000			$ 78,510,000
Historical Misapplication of GAAP Related to Timing of Recognizing Certain Expenses Incurred in Connection with New Business [Member]
Consolidated Statement of Shareholders' Equity [Abstract]
Balance at beginning of period	73,761,000	77,768,000			58,942,000	77,768,000	58,942,000	$ 58,942,000	58,942,000	$ 19,274,000	$ 1,262,000
Cumulative effect adjustment										892,000
Cumulative effect adjustment of error corrections											7,743,000
Net income (loss)		(5,495,000)	$ (2,650,000)	5,723,000	7,295,000		13,018,000	10,368,000	18,826,000	38,776,000	10,269,000
Balance at end of period		73,761,000							77,768,000	58,942,000	19,274,000
Historical Misapplication of GAAP Related to Timing of Recognizing Certain Expenses Incurred in Connection with New Business [Member] | As Previously Reported [Member]
Consolidated Statement of Shareholders' Equity [Abstract]
Balance at beginning of period	63,080,000	66,606,000			50,290,000	66,606,000	50,290,000	50,290,000	50,290,000	11,825,000	1,262,000
Cumulative effect adjustment										892,000
Cumulative effect adjustment of error corrections											0
Net income (loss)		(5,014,000)	(6,806,000)	6,301,000	7,626,000		13,927,000	7,121,000	16,316,000	37,573,000	10,563,000
Balance at end of period		63,080,000							66,606,000	50,290,000	11,825,000
Historical Misapplication of GAAP Related to Timing of Recognizing Certain Expenses Incurred in Connection with New Business [Member] | Adjustment [Member]
Consolidated Statement of Shareholders' Equity [Abstract]
Balance at beginning of period	$ 10,681,000	11,162,000			8,652,000	$ 11,162,000	8,652,000	8,652,000	8,652,000	7,449,000	0
Cumulative effect adjustment										0
Cumulative effect adjustment of error corrections											7,743,000
Net income (loss)		(481,000)	$ 4,156,000	$ (578,000)	$ (331,000)		$ (909,000)	$ 3,247,000	2,510,000	1,203,000	(294,000)
Balance at end of period		$ 10,681,000							$ 11,162,000	$ 8,652,000	$ 7,449,000