Investments - Debt, Equity and Other Securities - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
May 31, 2016	Jun. 30, 2016	Jun. 30, 2016
Investments Debt And Equity Securities [Line Items]
Realized and unrealized gains, net		$ 499,000	$ 729,000
Proceeds from sale of ownership interest in joint venture	$ 26,000,000
Maximum [Member]
Investments Debt And Equity Securities [Line Items]
Non controlling interest percentage in exchange of investment in joint venture		1.00%	1.00%

The cash inflow from the sale of an investment interest in a joint venture that the reporting entity has not previously accounted for using consolidation or the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromDivestitureOfInterestInJointVenture
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration