Stock-Based Compensation Plans (Narrative) (Detail) (USD $)	3 Months Ended		9 Months Ended						9 Months Ended								3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Rate	Sep. 30, 2013	Sep. 30, 2014 Two Thousand And Seven Plan [Member]	May 31, 2011 Two Thousand And Seven Plan [Member]	May 31, 2009 Two Thousand And Seven Plan [Member]	Jan. 31, 2007 Two Thousand And Seven Plan [Member]	Sep. 30, 2014 Two Thousand And Seven Plan [Member] Minimum [Member]	Sep. 30, 2014 Two Thousand And Seven Plan [Member] Maximum [Member]	Sep. 30, 2014 Nineteen Ninety Seven Plan [Member] Maximum [Member]	Sep. 30, 2014 Restricted Stock [Member] Minimum [Member]	Sep. 30, 2014 Restricted Stock [Member] Maximum [Member]	Sep. 30, 2014 Ltip Awards [Member]	Sep. 30, 2014 Ltip Awards [Member] Minimum [Member] Rate	Sep. 30, 2014 Ltip Awards [Member] Maximum [Member] Rate	Mar. 31, 2014 LTIP Performance-Based Stock Awards [Member]	Mar. 31, 2014 LTIP Performance-Based Cash Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved for issuance								500,000
Shares additionally approved for issuance						2,860,000	325,000
Shares available for future grants					447,565
Award vesting period, maximum, years									3 years	5 years		1 year	5 years	3 years
Share based payment award options term										7 years	10 years			7 years
Allocated Share-based Compensation Expense	$ 2,200,000	$ 2,000,000	$ 8,100,000	$ 6,500,000
Deferred Compensation Arrangement with Individual, Compensation Expense																	2,100,000	3,000,000
Weighted average grant date fair value per share of options granted			$ 11.96	$ 17.49
Aggregate intrinsic value of options exercised			$ 1,800,000	$ 777,000
Percentage Of Performance Based Award Payouts															0.00%	200.00%
Percentage Of Awards Paid In Performance Shares			17.00%