Employer Sponsored Benefit Plan (Trust's Assets at Fair Value) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 33,275	$ 40,680	$ 36,355
U.S. Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	14,272	15,141
Non U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	6,432	9,465
Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,896	2,713
U.S. Bond funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	8,528	10,461
Non U.S. Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	917	1,847
Real estate investment trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	170	155
Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,060	898
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	33,275	40,680
Fair Value, Inputs, Level 1 [Member] | U.S. Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	14,272	15,141
Fair Value, Inputs, Level 1 [Member] | Non U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	6,432	9,465
Fair Value, Inputs, Level 1 [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,896	2,713
Fair Value, Inputs, Level 1 [Member] | U.S. Bond funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	8,528	10,461
Fair Value, Inputs, Level 1 [Member] | Non U.S. Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	917	1,847
Fair Value, Inputs, Level 1 [Member] | Real estate investment trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	170	155
Fair Value, Inputs, Level 1 [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,060	898
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | U.S. Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Non U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | U.S. Bond funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Non U.S. Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Real estate investment trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | U.S. Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Non U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | U.S. Bond funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Non U.S. Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Real estate investment trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 0	$ 0