Other Noncurrent Assets - Other Noncurrent Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Other noncurrent assets:
Land held for development	$ 126.2	$ 129.2
Operating lease right-of-use assets	33.1
Restricted cash and cash equivalents	8.6	8.9
Land contract receivables	3.8	9.1
IBNR receivables	6.9	6.0
Marketable securities	4.9	4.8
Pension asset	3.4	2.7
Notes receivable - OPA	3.1	1.9
Other	13.7	12.7
Total	$ 203.7	$ 175.3