Reconciliation of Total Segment Assets to Total Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting [Abstract]
Total segment assets	$ 3,100,969	$ 3,144,625	$ 3,209,679
Other assets	48,421	48,054
Total assets	$ 3,149,390	$ 3,192,679