Employer Sponsored Benefit Plan (Trust's Assets at Fair Value) (Detail) - Domestic Pension Plan - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 35,413	$ 33,275	$ 40,680
U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	14,789	14,272
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	7,356	6,432
Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,027	1,896
U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	8,915	8,528
Non-U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,034	917
Real estate investment trusts
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	195	170
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,097	1,060
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	35,413	33,275
Level 1 | U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	14,789	14,272
Level 1 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	7,356	6,432
Level 1 | Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,027	1,896
Level 1 | U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	8,915	8,528
Level 1 | Non-U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,034	917
Level 1 | Real estate investment trusts
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	195	170
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,097	1,060
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Non-U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Real estate investment trusts
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Non-U.S. Bond funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Real estate investment trusts
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 0	$ 0