Stock-Based Compensation Plans (Narrative) (Detail) (USD $)	3 Months Ended					3 Months Ended								12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 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]	Mar. 31, 2014 Two Thousand And Seven Plan [Member] Minimum [Member]	Mar. 31, 2014 Two Thousand And Seven Plan [Member] Maximum [Member]	Mar. 31, 2014 Nineteen Ninety Seven Plan [Member]	Mar. 31, 2014 Restricted Stock [Member] Minimum [Member]	Mar. 31, 2014 Restricted Stock [Member] Maximum [Member]	Mar. 31, 2014 Ltip Awards [Member]	Mar. 31, 2014 Ltip Awards [Member] Minimum [Member]	Mar. 31, 2014 Ltip Awards [Member] Maximum [Member]	Dec. 31, 2013 LTIP Performance-Based Stock Awards [Member]	Dec. 31, 2013 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			361,834
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
Percentage of performance based award payouts												0.00%	200.00%
Allocated Share-based Compensation Expense	$ 3,800,000	$ 2,300,000
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	$ 17.59
Aggregate intrinsic value of options exercised	$ 911,000	$ 102,000