Operating Segments - Narrative (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Non-consolidated partner companies	27
Other Items [Member]
Segment Reporting Information [Line Items]
Total assets included cash, cash equivalents, cash held in escrow, and marketable securities	$ 130.2	$ 156.5