Return on Investment (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2011
Period 1
Class of Stock [Line Items]
ROI Percentage		200.00%
Redemption date	before the second anniversary of the date of issuance;
Period 2
Class of Stock [Line Items]
ROI Percentage		250.00%
Redemption date	on or after the second anniversary of the date of issuance, but before the third anniversary of the date of issuance;
Period 3
Class of Stock [Line Items]
ROI Percentage		300.00%
Redemption date	on or after the third anniversary of the date of issuance, but before the fourth anniversary of the date of issuance;
Period 4
Class of Stock [Line Items]
ROI Percentage		350.00%
Redemption date	on or after the fourth anniversary of the date of issuance, but before the fifth anniversary of the date of issuance;
Period 5
Class of Stock [Line Items]
ROI Percentage		400.00%
Redemption date	on or after the fifth anniversary of the date of issuance, but before the sixth anniversary of the date of issuance;
Period 6
Class of Stock [Line Items]
ROI Percentage		450.00%
Redemption date	on or after the sixth anniversary of the date of issuance, but before the seventh anniversary of the date of issuance;
Period 7
Class of Stock [Line Items]
ROI Percentage		500.00%
Redemption date	on or after the seventh anniversary of the date of issuance, but before the eighth anniversary of the date of issuance; and
Period 8
Class of Stock [Line Items]
ROI Percentage		550.00%
Redemption date	on or after the eighth anniversary of the date of issuance, but before the ninth anniversary of the date of issuance.